In World War I Svoboda deserted from the Austro-Hungarian army, while on the Eastern Front, and fought for the Czechoslovak Legion in Russia. He took part in the legendary battles of Zborov and Bakhmach and returned home through the famous "Siberian anabasis". He then worked at his father's estate before launching his military career in the Czechoslovak army.

In the early 1930s he taught at a military academy. After the German occupation in the spring of 1939 he became a member of a secret underground organization Obrana národa ("Defence of the nation"). It is supposed that at the same time he established a connection with the Soviet intelligence. In June 1939 he fled to Poland, forming an initial Czechoslovak military unit in Kraków, before falling into Soviet captivity during the Soviet invasion of Poland, however escaping a certain death after - as he related it after the war - asking his captors to call a phone number in Moscow where they could obtain personal information about him; this worked. After the outbreak of the German offensive against the USSR, Svoboda became head of the Czechoslovak military unit on the Eastern front. The unit fought the Germans for the first time in March 1943 near the Battle of Sokolovo in Ukraine. As a commander he also led troops of the 1st Czecholsovak Army Corps in the Battle of the Dukla Pass in the fall of 1944 when, after very heavy fighting, this unit managed to cross the Czechoslovak state border for the first time. Svoboda's charismatic leadership and personal bravery was highly valued by his commanding officer at the time, Soviet marshal Ivan Konev. Trusted by Klement Gottwald´s exile leadership and Soviet functionaries, he quickly climbed the military ranks becoming army general in August 1945.

In World War II a substantial part of Czechoslovakia was liberated by the Red Army and the 1st Czecholsovak Army Corps under the leadership of Svoboda. Svoboda was appointed Minister of Defense while being welcomed as a hero of the Eastern Front. The Soviet Union enjoyed a great popularity among the population and in the elections of 1946 the Communist Party of Czechoslovakia (CCP) won 38% of the vote nationwide. On 22 February 1948 (after the abdication of cabinet ministers from three democratic parties in protest against Communist practices) the Communist-dominated Trade Union Congress voted unanimously to replace the 12 departed ministers with Communists. As armed workers and the People's Militias took to the streets, Svoboda refused to quell the insurrection with military force, saying "the army will not march against the people". Two days later (and one day after a general strike in which 2,5 million citizens participated either out of fear or greed), the then Czechoslovak president Edvard Beneš accepted a solution asserted by Gottwald and filled the vacant government posts with Communist candidates, thus creating a 25-seat government with 13 Communist ministers. The takeover was completely bloodless. Svoboda, whose label had been that of an "apolitical" minister since the first days of his term, then joined the Communist Party whose de facto Trojan horse he had been all the time and was elected a deputy to the National Assembly.

Svoboda was forced out of the army (in which he had reached the rank of General in November 1945) in 1950 under pressure from Stalin. He was deputy Prime Minister of the Czechoslovak government in 1950 and 1951. In the purges which followed, Svoboda was imprisoned and "recommended" to save his image by committing suicide, but eventually released and stripped of all offices. His return to public life took place upon a personal wish of Khrushchev, whom Svoboda had met during the war, and he subsequently headed the Klement Gottwald Military Academy.

He was awarded the title People's Hero of Yugoslavia in November 1965. Svoboda was also awarded the title Hero of the Soviet Union (on 24 November 1965), and Hero of the Czechoslovak Socialist Republic (being awarded the latter title again in 1970 and 1975). He was also awarded the Lenin Peace Prize (1970).

After the ending of the Antonín Novotný regime, in the period known as the Prague Spring, Svoboda was elected President of Czechoslovakia on 30 March 1968, on the recommendation of Alexander Dubček, the First Secretary. He was an acceptable candidate both for Czechs and Slovaks plus, as a war hero and a victim of Stalinist purges, he enjoyed a very high esteem among the population.

Svoboda then gave a mild consent to the reform process of the new Party leadership until the Soviet intervention in August 1968. Horrified at his experiences in two world wars, he signed an order preventing the Czechoslovak Army from getting involved with the invading Warsaw Treaty troops, and he refused to appoint the so-called peasant-workers´government, despite Leonid Brezhnev´s demands that he do so. He also secured the release of Dubček when the latter, and other members of the Czechoslovak government, were abducted to the Soviet Union in August 1968. To bring this result about, Svoboda threatened - as a famous Czechoslovak and Soviet war hero - to put a bullet into his head in the presence of Brezhnev. Nevertheless, Svoboda could do nothing to prevent Brezhnev from forcing the Czechoslovak representatives to sign the notorious Moscow protocols, which meant a factual capitulation as they were kept secret and provided the Warsaw Pact armies with a factual licence to a "temporary stay" (as it was called later at an October parliamentary session) in Czechoslovakia. The protocols also obliged the Party leadership to promote political, cultural and other changes to stop the reform process. Svoboda also supported then Minister of Defence Martin Dzúr who ordered the Czechoslovak army to not show any resistance. Given the public outrage and resistance, Svoboda's arbitrary action was in fact in accord with Brezhnev's intent.

Svoboda survived the removal of reformist Communists in Czechoslovakia while passively witnessing the Party purges and suffocation of former civic liberties. He even helped silence the disobedient press and also contributed to Dubček's ouster from his post in April 1969. Always he continued to believe, and maintain, that his submissive conduct helped save thousands of lives from "immense consequences"; and he defended this policy by invoking his own memories of the horrors of war.

After resisting stubbornly the attempts of Gustav Husák´s new leadership to oust him from the presidential office, Svoboda had to be forced to retire in 1975 through a constitutional act (paragraph 64 Nr.143/1968 Sb.). This act stated that the Federal Assembly had the right to elect a new president, provided that the existing one was, for a year or more, unable to carry out his office's duties. In Svoboda's case, his ill health made the act relevant.

Despite being misused by politicians for their goals several times, Svoboda still enjoys a high credit among the Czechoslovak population, probably due to his brave stance and fortitude on several occasions during crucial moments of the Czechoslovak history; and squares and streets in both the Czech and Slovak Republic continue to bear his name, while those of other communist leaders were removed after the Velvet Revolution. His attitude can be perhaps explained by his own words: All I have ever done must be measured by my intention to serve best my people and my country.