Toyotomi Hideyoshi had been given the nickname Kozaru, meaning "little monkey", from his lord Oda Nobunaga because his facial features and skinny form resembled that of a monkey. He was also known as the "bald rat."

Many legends describe Hideyoshi being sent to study at a temple as a young man, but he rejected temple life and went in search of adventure. Under the name Kinoshita Tōkichirō (木下 藤吉郎^?), he first joined the Imagawa clan as a servant to a local ruler named Matsushita Yukitsuna. He traveled all the way to the lands of Imagawa Yoshimoto, daimyo of Suruga Province, and served there for a time, only to abscond with a sum of money entrusted to him by Matsushita Yukitsuna.

Around 1557 he returned to Owari Province and joined the Oda clan, now headed by Oda Nobunaga, as a lowly servant. He became one of Nobunaga's sandal - bearers and was present at the Battle of Okehazama in 1560 when Nobunaga defeated Imagawa Yoshimoto to become one of the most powerful warlords in the Sengoku period. According to his biographers, he supervised the repair of Kiyosu Castle, a claim described as "apocryphal", and managed the kitchen. In 1561, Hideyoshi married Nene who was Asano Nagamasa's adopted daughter. He carried out repairs on Sunomata Castle with his younger brother Toyotomi Hidenaga and the bandits Hachisuka Masakatsu and Maeno Nagayasu. Hideyoshi's efforts were well received because Sunomata was in enemy territory. He constructed a fort in Sunomata, according to legend overnight, and discovered a secret route into Mount Inaba after which much of the garrison surrendered.

Hideyoshi was very successful as a negotiator. In 1564 he managed to convince, mostly with liberal bribes, a number of Mino warlords to desert the Saitō clan. Hideyoshi approached many Saitō clan samurai and convinced them to submit to Nobunaga, including the Saitō clan's strategist Takenaka Hanbei.

Nobunaga's easy victory at Inabayama Castle in 1567 was largely due to Hideyoshi's efforts, and despite his peasant origins, Hideyoshi became one of Nobunaga's most distinguished generals, eventually taking the name Hashiba Hideyoshi (羽柴 秀吉). The new surname included two characters, one each from Oda's two other right - hand men, Niwa Nagahide and Shibata Katsuie.

Hideyoshi led troops in the Battle of Anegawa in 1570 in which Oda Nobunaga allied with future rival Tokugawa Ieyasu (who would eventually displace Hideyoshi's son and rule Japan) to lay siege to two fortresses of the Azai and Asakura clans. In 1573, after victorious campaigns against the Azai and Asakura, Nobunaga appointed Hideyoshi daimyo of three districts in the northern part of Ōmi Province. Initially based at the former Azai headquarters in Odani, Hideyoshi moved to Kunitomo, and renamed the city Nagahama in tribute to Nobunaga. Hideyoshi later moved to the port at Imahama on Lake Biwa. From there he began work on Imahama Castle and took control of the nearby Kunitomo firearms factory that had been established some years previously by the Azai and Asakura. Under Hideyoshi's administration the factory's output of firearms increased dramatically. Nobunaga sent Hideyoshi to Himeji Castle to conquer Chūgoku region in 1576.

After the assassinations at Honnō-ji of Oda Nobunaga and his eldest son Nobutada in 1582 at the hands of Akechi Mitsuhide, Hideyoshi defeated Akechi at the Battle of Yamazaki.

At a meeting at Kiyosu to decide on a successor to Nobunaga, Hideyoshi cast aside the apparent candidate, Oda Nobutaka and his advocate, Oda clan's chief general, Shibata Katsuie, by supporting Nobutada's young son, Oda Hidenobu. Having won the support of the other two Oda elders, Niwa Nagahide and Ikeda Tsuneoki, Hideyoshi established Hidenobu's position, as well as his own influence in the Oda clan. Tension quickly escalated between Hideyoshi and Katsuie, and at the Battle of Shizugatake in the following year, Hideyoshi destroyed Katsuie's forces and thus consolidated his own power, absorbing most of the Oda clan into his control.

In 1583, Hideyoshi began construction of Osaka Castle. Built on the site of the temple Ishiyama Honganji destroyed by Nobunaga, the castle would become the last stronghold of the Toyotomi clan after Hideyoshi's death.

Nobunaga's other son, Oda Nobukatsu, remained hostile to Hideyoshi. He allied himself with Tokugawa Ieyasu, and the two sides fought at the inconclusive Battle of Komaki and Nagakute. It ultimately resulted in a stalemate, although Hideyoshi's forces were delivered a heavy blow. Finally, Hideyoshi made peace with Nobukatsu, ending the pretext for war between the Tokugawa and Hashiba clans. Hideyoshi sent Tokugawa Ieyasu his younger sister Asahi no kata and mother Ōmandokoro (大政所) as hostages. Ieyasu eventually agreed to become a vassal of Hideyoshi.

Like Nobunaga before him, Hideyoshi never achieved the title of shogun. Instead, he arranged to have himself adopted into the Fujiwara Regents House, and secured a succession of high imperial court titles including, in 1585 the prestigious position of regent (kampaku). In 1586, Hideyoshi was formally given the name Toyotomi by the imperial court. He built a lavish palace, the Jurakudai, in 1587 and entertained the reigning Emperor Go-Yozei the following year.

Afterwards, Hideyoshi subjugated Kii Province and conquered Shikoku under the Chōsokabe clan. He also took control of Etchū Province and conquered Kyūshū. In 1587, Hideyoshi banished Christian missionaries from Kyūshū to exert greater control over the Kirishitan daimyo. However, since he made much of trade with Europeans, individual Christians were overlooked unofficially. In 1588, Hideyoshi forbade ordinary peasants from owning weapons and started a sword hunt to confiscate arms. The swords were melted down to create a statue of the Buddha. This measure effectively stopped peasant revolts and ensured greater stability at the expense of freedom of the individual daimyo. The 1590 Siege of Odawara against the Late Hōjō clan in Kantō eliminated the last resistance to Hideyoshi's authority. His victory signified the end of the Sengoku period. During this siege, Hideyoshi proposed that Ieyasu currently controlled five provinces were submitted, and Ieyasu receive the eight Kantō provinces that Kitajo ruled. Ieyasu accepted this proposal and Date Masamune pledged loyalty to the Hideyoshi.

In February 1591, Hideyoshi ordered Sen no Rikyū to commit suicide. Rikyū had been a trusted retainer and master of the tea ceremony under both Hideyoshi and Nobunaga. Under Hideyoshi's patronage, Rikyū made significant changes to the aesthetics of the tea ceremony that had lasting influence over many aspects of Japanese culture. Even after he ordered Rikyū's suicide, Hideyoshi is said to have built his many construction projects based upon principles of beauty promoted by Rikyū.

Following Rikyū's death, Hideyoshi turned his attentions from tea ceremony to Noh, which he had been studying in the Komparu style since becoming kampaku. During his brief stay in Nagoya Castle in what is today Saga prefecture, on Kyūshū, Hideyoshi memorized the shite (lead roles) parts of ten Noh plays, which he then performed, forcing various daimyō to accompany him onstage as the waki (secondary, accompanying role). He even performed before the Emperor.

The stability of the Toyotomi dynasty after Hideyoshi's death was put in doubt with the death of his only son Tsurumatsu in September 1591. The three year old was his only child. When his half - brother Hidenaga died shortly after his son, Hideyoshi named his nephew Hidetsugu his heir, adopting him in January 1592. Hideyoshi resigned as kampaku to take the title of taikō (retired regent). Hidetsugu succeeded him as kampaku.

His health beginning to falter, but still yearning for some accomplishment to solidify his legacy, Hideyoshi adopted the dream of a Japanese conquest of China that Oda Nobunaga had contemplated, and launched two ill fated invasions of Korea. Though he actually intended to conquer Ming China, Hideyoshi had been communicating with the Koreans since 1587 requesting unmolested passage into China. As allies of Ming China, the Koreans at first refused talks entirely, and in April and July 1591 refused demands that Japanese troops be allowed to march through Korea. The Koreans were also concerned that allowing Japanese troops to march through Korea (Chosun) would mean that masses of Ming Chinese troops would battle Hideyoshi's troops on Korean soil before they could reach China — effectively ruining the Chosun economy. In August, Hideyoshi ordered preparations for invasion.

In the first campaign, Hideyoshi appointed Ukita Hideie to the field marshal, and had them go to the Korean peninsula in April, 1592. Konishi Yukinaga occupied Seoul, the capital of the Joseon Dynasty on May 10, and in only four months, Hideyoshi's forces had a route into Manchuria and occupied much of Korea. Korean king Seonjo of Joseon escaped to Pyongyang, and requested military intervention from China. In 1593, Ming Chinese Emperor Wanli sent an army under general Li Rusong to block the planned invasion of China and recapture the Korean peninsula. Li recaptured Pyongyang, and surrounded Seoul. Ishida Mitsunari massed Japanese forces in Seoul and halted Li Rusong and his forces with a serious counterattack. The war reached a deadlock, and after the conclusion of a cease fire agreement, Japanese troops retreated to Japan.

The birth of Hideyoshi's second son, Hideyori, in 1593 created a potential succession problem. To avoid it, Hideyoshi exiled his nephew and heir Hidetsugu to Mount Kōya and then ordered him to commit suicide in August 1595. Hidetsugu's family members who did not follow his example were then murdered in Kyoto, including 31 women and several children.

On February 5, 1597, Toyotomi Hideyoshi had twenty - six Christians killed as an example to Japanese who wanted to convert to Christianity. They are known as the Twenty - six Martyrs of Japan. They included five European Franciscan missionaries, one Mexican Franciscan missionary, three Japanese Jesuits and seventeen Japanese laymen including three young boys. They were executed by public crucifixion in Nagasaki.

After several years of negotiations (broken off because envoys of both sides falsely reported to their masters that the opposition surrendered), Hideyoshi appointed Kobayakawa Hideaki to lead the invasion forces, but their efforts on the Korean peninsula met with less success than the first invasion. Japanese troops remained pinned in Gyeongsang province. By June 1598, The Japanese forces fought with desperation, turning back several Chinese offensives in Suncheon and Sacheon as the Ming army prepared for a final assault. The Koreans guerrilla warfare, aided by the fact that they were fighting on their homeland, continually harassed Japanese forces. While Hideyoshi's last battle at So-chon, was a major Japanese victory, all three parties to the war were exhausted. and Hideyoshi himself now accepted that the war could not be won. He told his commander in Korea: "Don't let my soldiers become spirits in a foreign land.". Toyotomi Hideyoshi died September 18, 1598. His death was kept secret by the Council of Five Elders to preserve morale, and Japanese troops were withdrawn from the Korean peninsula.

Because of his failure to capture Korea, Hideyoshi's forces were unable to invade China. Rather than strengthen his position, the military expeditions left his clan's coffers and fighting strength depleted, his vassals at odds over responsibility for the failure, and the clans that were loyal to the Toyotomi name weakened. The dream of a Japanese empire encompassing Asia ended with Hideyoshi. The Tokugawa government not only prohibited any military expeditions to the mainland, but closed Japan to nearly all foreigners during the years of the Tokugawa Shogunate. It was not until the late 19th century that Japan would again fight a war against China through Korea, using much the same route that Hideyoshi's invasion force had used.

After his death, the other members of the Council of Five Regents were unable to keep the ambitions of Tokugawa Ieyasu in check. Two of Hideyoshi's top generals Katō Kiyomasa and Fukushima Masanori had fought bravely during the war, but returned to find the Toyotomi clan castellan Ishida Mitsunari in power. He held the generals in low esteem, and they sided with Tokugawa Ieyasu. Hideyoshi's underaged son and designated successor Hideyori lost the power his father once held, and Tokugawa Ieyasu was declared Shogun following the Battle of Sekigahara.

Toyotomi Hideyoshi changed Japanese society in many ways. These include imposition of a rigid class structure, restriction on travel, and surveys of land and production.

Class reforms affected commoners and warriors. During the Sengoku period, it had become common for peasants to become warriors, or for samurai to farm due to the constant uncertainty caused by the lack of centralized government and always tentative peace. Upon taking control, Hideyoshi decreed that all peasants be disarmed completely. Conversely, he required samurai to leave the land and take up residence in the castle towns. This solidified the social class system for the next 300 years.

Furthermore, he ordered comprehensive surveys and a complete census of Japan. Once this was done and all citizens were registered, he required all Japanese to stay in their respective han (fiefs) unless they obtained official permission to go elsewhere. This ensured order in a period when bandits still roamed the countryside and peace was still new. The land surveys formed the basis for systematic taxation.

In 1590, Hideyoshi completed construction of the Osaka Castle, the largest and most formidable in all Japan, to guard the western approaches to Kyoto. In that same year, Hideyoshi banned "unfree labor" or slavery; but forms of contract and indentured labor persisted alongside the period penal codes' forced labor.

Hideyoshi also influenced the material culture of Japan. He lavished time and money on the tea ceremony, collecting implements, sponsoring lavish social events, and patronizing acclaimed masters. As interest in the tea ceremony rose among the ruling class, so too did demand for fine ceramic implements, and during the course of the Korean campaigns, not only were large quantities of prized ceramic ware confiscated, many Korean artisans were forcibly relocated to Japan.

Inspired by the dazzling Golden Pavilion in Kyoto, he also constructed a fabulous portable tea room, covered with gold leaf and lined inside with red gossamer. Using this mobile innovation, he was able to practice the tea ceremony wherever he went, powerfully projecting his unrivaled power and status upon his arrival.

Politically, he set up a governmental system that balanced out the most powerful Japanese warlords (or daimyo). A council was created to include the most influential lords. At the same time, a regent was designated to be in command.

Just prior to his death, Hideyoshi hoped to set up a system stable enough to survive until his son grew old enough to become the next leader. A Council of Five Elders (五大老 go-tairō^?) was formed, consisting of the five most powerful daimyo. Following the death of Maeda Toshiie, however, Tokugawa Ieyasu began to secure alliances, including political marriages (which had been forbidden by Hideyoshi). Eventually, the pro-Toyotomi forces fought against the Tokugawa in the Battle of Sekigahara. Ieyasu won and received the title of Seii-tai Shogun two years later.

Hideyoshi is commemorated at several Toyokuni Shrines scattered over Japan.

Ieyasu left in place the majority of Hideyoshi's decrees and built his shogunate upon them. This ensured that Hideyoshi's cultural legacy remained. In a letter to his wife, Hideyoshi wrote:

Because of his low birth and high nobility, Toyotomi Hideyoshi had quite a few names throughout his life. At birth, he was given the name Hiyoshi-maru 日吉丸. At genpuku he took the name Kinoshita Tōkichirō (木下 藤吉郎^?). Later, he was given the surname Hashiba, and the honorary court office Chikuzen no Kami; as a result he was styled Hashiba Chikuzen no Kami Hideyoshi (羽柴筑前守秀吉^?). His surname remained Hashiba even as he was granted the new uji or sei (氏 or 姓, clan name) Toyotomi by the emperor. His name is correctly Toyotomi no Hideyoshi. Using the writing system of his time, his name is written as 豐臣 秀吉.

The Toyotomi uji was simultaneously granted to a number of Hideyoshi's chosen allies, who adopted the new uji "豊臣朝臣" (Toyotomi no asomi, courtier of Toyotomi). The Catholic sources of the time referred to him as "emperor Taicosama" (from taikō, a retired kampaku (Sesshō and Kampaku), and the honorific sama). His nickname was "Monkey" (Saru), allegedly given by Oda Nobunaga because of his facial resemblance to a monkey. This recognition directly contributed to the popular image of Toyotomi Hideyoshi being a monkey styled person, both in appearance and mode of behaviour.