During the Great Northern War, multiple candidates had emerged after the death of John III Sobieski for the elective kingship of Poland (which also included the Grand Duchy of Lithuania as part of the Poland-Lithuanian Commonwealth).

Backed by powerful neighbors in Russia and Austria, the Sejm elected Augustus the Strong, Elector of Saxony to succeed John III in 1697 as August II.

In 1709, Charles XII of Sweden, Stanisław's main supporter, suffered a defeat by the Russians at the Battle of Poltava, and was subsequently driven into exile in the Ottoman Empire.

His retaking of the Polish throne in 1733 formed the backdrop for Un giorno di regno, an opera by composer Giuseppe Verdi and librettist Felice Romani, which premiered in 1840.

The following year, Stanisław was selected by Charles XII of Sweden after a successful Swedish invasion of Poland, to supersede Augustus II, who was hostile towards the Swedes.

Leszczyński was a young man of blameless antecedents, respectable talents, and came from an ancient family, but certainly without sufficient force of character or political influence to sustain himself on so unstable a throne.

Nevertheless, with the assistance of a bribing fund and an army corps, the Swedes succeeded in procuring his election by a scratch assembly of half a dozen castellans and a few score of noblemen on 12 July 1704.

A few months later, Stanisław was forced by a sudden inroad of Augustus II to seek refuge in the Swedish camp, but finally on 24 September 1705, he was crowned king with great splendor.

On 30 June 1734, a Russian army of 20,000 under Peter Lacy, after proclaiming Frederick Augustus II of Saxony as king in Warsaw, proceeded to besiege Stanisław at Danzig, where he was entrenched with his partisans (including the Primate and the French and Swedish ministers) to await the relief that had been promised by France.

On 17 March 1735, Marshal Burkhard Christoph von Münnich superseded Peter Lacy, and on 20 May 1735 the long-expected French fleet appeared and disembarked 2,400 men on Westerplatte.

He reappeared at Königsberg (where he briefly met the future King Frederick the Great of Prussia), whence he issued a manifesto to his partisans which resulted in the formation of a confederation on his behalf, and the despatch of a Polish envoy to Paris to urge France to invade Saxony with at least 40,000 men.

In his last years, his close friend, the Hungarian-born Marshal of France Ladislas Ignace de Bercheny lived on his estate to provide company.

Leszczyński died aged 88 in 1766 as a result of serious burns – his silk attire had caught fire from a spark while the King was asleep near the fireplace in his palace in Lunéville on 5 February.

Loosely based on an incident of King Stanisław's life are the play Le faux Stanislas written by the Frenchman Alexandre Vincent Pineu-Duval in 1808, transformed into the opera Un giorno di regno, ossia Il finto Stanislao (A One-Day Reign, or The Pretend Stanislaus, but often translated into English as King for a Day) by Giuseppe Verdi, to an Italian libretto written in 1818 by Felice Romani.