Anna Leopoldovna was born in Rostock on 7 October 1718. She was the daughter of Duke Carl Leopold of Mecklenburg-Schwerin and Ekaterina Ioannovna, elder sister of Empress Anna Ioannovna and niece of Peter the Great. In 1722, Ekaterina ran away from her tyrannical husband to Russia, taking her daughter with her.
Empress Anna Ioannovna decided to bring her niece up herself. On 12 May 1733, at the age of fourteen, the girl converted to Russian Orthodoxy and took the name of Anna in honour of her aunt.
As Anna Ioannovna did not have any children of her own, she decided to marry her niece in an attempt to produce a male heir for the Russian throne. Her choice fell on Prince Anton Ulrich of Brunswick-Wolfenbüttel. Anton was the nephew of the Austrian empress and the son of Tsarevich Alexei’s sister-in-law, making him a cousin of Peter II.
Prince Anton Ulrich was summoned to St Petersburg in 1733, where he did not create a favourable impression on either the empress or his future bride. By then, however, the offer had already been made. The prince entered the Russian army as a lieutenant colonel of the Cuirassier Guards Regiment. A contemporary described him as “an extremely good chap, but that was all; he had a kind heart, but no brains or energy.”
While her future husband was away at war, fighting Turkey, Anna Leopoldovna fell in love with Carl Moritz Linar, the "handsome and swashbuckling" Saxon ambassador. In 1735, her aunt learnt of their love affair and asked the Saxon government to recall the ambassador. Linar was sent home in 1736 and the empress kept a close watch on her niece.
Distraught at being forced to part with her lover, Anna Leopoldovna became withdrawn and unsociable, spending her days reading French and German novels. When the empress’s favourite Biron attempted to marry her to his own son Peter, a drunken boor, Anna rejected this offer with unconcealed horror.
Anna Ioannovna did not give up her attempts to marry her niece and produce a male heir for the Russian throne. In June 1739, on behalf of Prince Anton Ulrich, the Austrian ambassador formally asked the empress for the princess’s hand. They were married in St Petersburg on 3 July 1739, in the Church of the Nativity of the Blessed Virgin, on the site of the future Kazan Cathedral. Witnesses reported that the groom looked “like a human sacrifice,” while the bride’s eyes were red from crying. Anna spent her wedding night walking alone in the Summer Garden. When the empress learnt of this the next morning, she angrily slapped her niece across the face.
When Empress Anna Ioannovna died in October 1740, the throne passed to their two-month-old son Ioann with Biron as regent. On the night of 9 November 1740, Biron was overthrown and exiled to Pely in Siberia. The new regent was Anna. One of Anna’s first acts as regent was to restore her lover, Linar, to St Petersburg, where he was given a position at the court. Uninterested in affairs of state, she left the government of the country to Heinrich Johann Friedrich Ostermann, while she herself spent her time in bed or playing cards.
Anna died on 7 March 1747 of post-natal fever. She was buried alongside her grandmother, Praskovia Fedorovna, in the St Alexander Nevsky Monastery.