Francis was the oldest surviving son of Leopold, Duke of Lorraine, and the French princess Élisabeth Charlotte d'Orléans.

Francis died in 1765 and was succeeded by their son, Joseph II, who co-ruled Austria alongside Maria Theresa.

[2] At the age of 15, when he was brought to Vienna, he was established in the Silesian Duchy of Teschen, which had been mediatised and granted to his father by the Emperor in 1722.

[3] During a subsequent visit to England, Francis was made a Master Mason at another specially convened lodge at Houghton Hall, the Norfolk estate of British Prime Minister Robert Walpole.

Under its terms, Stanisław I, the father-in-law of King Louis XV and the losing claimant to the Polish throne, received Lorraine, while Francis, in compensation for his loss, was made heir to the Grand Duchy of Tuscany, which he would inherit in 1737.

In March 1736, the Emperor persuaded Francis, his future son-in-law, to secretly exchange Lorraine for the Grand Duchy of Tuscany.

France had demanded that Maria Theresa's fiancé surrender his ancestral Duchy of Lorraine to accommodate the deposed King of Poland.

The Emperor considered other possibilities (such as marrying her to the future Charles III of Spain) before announcing the engagement of the couple.

On 1 February, Maria Theresa sent Francis a letter: she would withdraw from her future reign, when a male successor for her father appeared.

He had a natural fund of good sense and brilliant business capacity and was a useful assistant to Maria Theresa in the laborious task of governing the complicated Austrian dominions, but he was not active in politics or diplomacy.

[8] Heavily indebted and on the verge of bankruptcy at the end of the Seven Years' War, the Habsburg monarchy was in a better financial condition than France or Great Britain in the 1780s.

Francis was a serial adulterer; many of his affairs well-known and indiscreet, notably one with Princess Maria Wilhelmina of Auersperg, who was thirty years his junior.

Maria Theresa and Francis I had sixteen children, amongst them the last pre-revolutionary queen consort of France, their youngest daughter, Marie Antoinette (1755–1793).

The full titulature of Francis after he and his wife Maria Theresa succeeded her father Charles VI & III to the thrones of the Holy Roman Empire and the vast realms of Central and Eastern Europe was: "His Imperial and Royal Apostolic Majesty, Francis I, by the Grace of God elected Holy Roman Emperor forever Augustus, King of Germany, King of Hungary, of Bohemia, of Croatia, of Dalmatia, of Slavonia, of Galicia, of Lodomeria, of Italy, of Cumania, of Bulgaria, of Serbia, etc.