He was born at Beşiktaş Sahil Palace or at Topkapı Palace, both in Constantinople. His mother was his father's first wife in 1839, Valide Sultan Bezmiâlem, originally named Suzi (1807 - 1852), a Circassian slave. Abdülmecid received a European education and was a fluent speaker of the French language while being interested in literature and classical music like Abdülaziz who succeeded him. He was an advocate of reforms like his father Mahmud II, and was lucky enough to have the support of progressionist viziers like Mustafa Reşit Pasha, Mehmet Emin Ali Paşa and Fuat Pasha. Throughout his reign he had to struggle against conservatives who opposed his reforms. Abdülmecid was also the first emperor to personally listen to the public's complaints in special reception days, usually every Friday, without any middlemen. Abdülmecid toured the empire's territories to see in first person how the Tanzimat reforms were being applied; travelling to İzmit, Mudanya, Bursa, Gallipoli, Çanakkale, Lemnos, Lesbos and Chios in 1844. He toured the Balkan provinces in 1846.

When Abdülmecid succeeded to the throne, the affairs of the Ottoman Empire were in an extremely critical state. At the very time his father died, the news was on its way to Constantinople that the empire's army had been defeated at Nizip by that of the rebel Egyptian viceroy, Muhammad Ali. The empire's fleet was at the same time on its way to Alexandria, where it was handed over to the same enemy by its commander Ahmed Fevzi Pasha, on the pretext that the young sultan's advisers were sold to Russia. However, through the intervention of the European powers, Muhammad Ali was obliged to come to terms, and the Ottoman Empire was saved from further attacks while its territories in Syria, Lebanon and Palestine were restored.

In compliance with his father's express instructions, Abdülmecid immediately carried out the reforms to which Mahmud II had devoted himself. In November 1839 an edict known as theHatt-ı Şerif of Gülhane, also known as Tanzimat Fermanı was proclaimed, consolidating and enforcing these reforms. The edict was supplemented at the close of the Crimean War by a similar statute issued in February 1856, named the Hatt-ı Hümayun. By these enactments it was provided that all classes of the sultan's subjects should have security for their lives and property; that taxes should be fairly imposed and justice impartially administered; and that all should have full religious liberty and equal civil rights. The scheme met with keen opposition from the Muslim governing classes and the ulema, or religious authorities, and was but partially put in force, especially in the remoter parts of the empire; and more than one conspiracy was formed against the sultan's life on account of it.

The most important measures of reform promoted by Abdülmecid were:

• Introduction of the first Ottoman paper banknotes (1840)
• Reorganization of the army (1843 - 1844)
• Adoption of an Ottoman national anthem and Ottoman national flag (1844)
• Reorganization of the finance system according to the French model
• Reorganization of the Civil and Criminal Code according to the French model
• Establishment of the Meclis-i Maarif-i Umumiye (1845) which was the prototype of the First Ottoman Parliament (1876)
• Institution of a council of public instruction (1846)
• Establishment of the first modern universities and academies (1848)
• Abolition of an unfairly imposed capitation tax which imposed higher tariffs on non-Muslims (1856)
• Non-Muslims were allowed to become soldiers (1856)
• Various provisions for the better administration of the public service and for the advancement of commerce

Another notable reform was that the turban was officially outlawed for the first time during Abdülmecid's reign, in favour of the fez. European fashions were also adopted in full swing by the Court. (The fez itself was later banned with the "Hat Law" in 1925 by the Republican National Assembly which had already abolished the sultanate and proclaimed the Turkish Republic in 1923).

Samuel Morse received his first ever patent for the telegraph in 1847, at the old Beylerbeyi Palace (the present Beylerbeyi Palace was built in 1861 - 1865 on the same location) in Constantinople, which was issued by Sultan Abdülmecid who personally tested the new invention.

When Kossuth and others sought refuge in Turkey after the failure of the Hungarian rising in 1849, the sultan was called on by Austria and Russia to surrender them, but he refused. He also would not allow the conspirators against his own life to be put to death. The 1911 Encyclopædia Britannica says of him, "Abdülmecid bore the character of being a kind and honourable man, if somewhat weak and easily led. Against this, however, must be set down his excessive extravagance, especially towards the end of his life."

In 1844 he created a new coin with that name and in 1852 he instituted the Order of the Medjidie.

The Ottoman Empire took its first foreign loans on 25 August 1854 during the Crimean War. This major foreign loan was followed by those of 1855, 1858 and 1860, which culminated in default and led to the alienation of European sympathy from Turkey and indirectly to the dethronement and death of Abdülâziz in the following years.

He was made the 717th Knight of the Order of the Garter in 1856 and the 52nd Grand Cross of the Order of the Tower and Sword.

Abdülmecid died of tuberculosis (like his father) at the age of 39 in Constantinople on 25 June 1861, where he was buried, and was succeeded by his brother, Abdülâziz, the oldest survivor of the family of Osman.

A popular tale says that in 1845, the onset of the Great Irish Famine resulted in over 1,000,000 deaths. Ottoman Sultan Abdülmecid declared his intention to send 10,000 sterling to Irish farmers but Queen Victoria requested that the Sultan send only 1,000 sterling, because she had sent only 2,000 sterling. The Sultan sent the 1,000 sterling but also secretly sent 3 ships full of food. The English courts tried to block the ships, but the food arrived at Drogheda harbor and was left there by Ottoman Sailors. Due to this the Irish people, especially those in Drogheda, are friendly to the Turks.

He married many times and left several sons, of whom four eventually succeeded to the throne.