Gay-Lussac was born at Saint-Léonard-de-Noblat in the present-day department of Haute-Vienne.
His father, Anthony Gay, son of a doctor, was a lawyer and prosecutor and worked as a judge in Noblat Bridge. Father of two sons and three daughters, he owned much of the Lussac village and began to add the name of this hamlet to his name, following a custom of the Ancien Régime. Towards the year 1803, father and son formally adopted the name Gay-Lussac. During the Revolution, under the Law of Suspects, his father, former king's attorney, was imprisoned in Saint Léonard from 1793 to 1794.
Gay-Lussac received his early education at the hands of the Catholic Abbey of Bourdeix. In the care of the Abbot of Dumonteil, he began his education in Paris, finally entering the École Polytechnique in 1798.
Three years later, Gay-Lussac transferred to the École des Ponts et Chaussées, and shortly afterward was assigned to C. L. Berthollet as his assistant. In 1804 he was appointed répétiteur (demonstrator) to Antoine François Fourcroy at the École Polytechnique, whom he succeeded in 1809 as professor of chemistry. From 1809 to 1832, he was also the professor of physics at the Sorbonne, a post which he only resigned for the chair of chemistry at the Jardin des Plantes. In 1821, he was elected a foreign member of the Royal Swedish Academy of Sciences. In 1831 he was elected to represent Haute-Vienne in the chamber of deputies, and in 1839 he entered the chamber of peers. He was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 1832.
Gay-Lussac married Geneviève-Marie-Joseph Rojot in 1809. He had first met her when she worked as a linen drapers shop assistant; he noticed she was studying a chemistry textbook under the counter, which led to their acquaintance. The couple had five children, of whom the eldest (Jules) became a student of Justus Liebig in Giessen. Some publications by Jules are mistaken as his fathers today since they share the same first initial (J. Gay-Lussac).
Gay-Lussac had a reputation as one of the greatest European scientists of his day, well justified by his innumerable discoveries in both chemistry and physics. The restored royalty made him a Peer of France, although he worked politically with the anti-clerical party. He was closely associated with François Arago.
Gay-Lussac died in Paris, and his grave is there at Père Lachaise Cemetery. His name is one of the 72 names inscribed on the Eiffel Tower.