The name of the country appears for the first time in a document of the 937 as Garniano, perhaps derived from the Latin stem Garenius. Documents of Tito Livio and headstones, testify to the presence of Etruscans, Celts, Cenomani and Romans.
From 1350 to 1426 the territory of Gargnano it was a dominion of the Visconti, later a dominion of the Republic of Venice.
Giovanni Beatrice, called Zanzanù, and Eliseo Baruffaldo, brigands of the XVII century.
Pietro Bellotto, Baroque painter.
Lorenzo Fiorini, Domenico Pattuccelli and Tommaso Chiaromonte, volunteers in the southern army of Giuseppe Garibaldi during the military campaign of 1860.
Alexander Bettoni Cazzago, soldier, partisan and horseman. Won the Siena Square dressage competition for 1942. As colonel of the Third Regiment of the Savoy Cavalry in 1942 he led charges in the Russian campaign that are among the last uses of cavalry in modern warfare.
Erika Blanc, actress.
Cesare Lievi, theatre director, poet and dramatist.
Benito Mussolini, during the Italian Social Republic (the Republic of Saló) lived in the Villa delle Orsoline (Villa Feltrinelli).
David Herbert Lawrence, novelist lived in Gargnano from 18 September 1912 to 30 March 1913 with Frieda Weekley von Richthofen.