Influenced by Chardin, his skill is demonstrated in his portraits, in a simplicity with the finest detail, or in the serenity of his scenes of the bridges, parks, and streets of Paris.

With James McNeill Whistler, Jean-Louis Forain, and Yamamoto, La Gándara illustrated Les Chauves-Souris ("The Bats") by the French poet Robert de Montesquiou.

The first exhibition of La Gándara's work organised in New York by Durand-Ruel in 1898 was a major success and confirmed the painter as one of the masters of his time.

Although his fame faded rapidly after his death, growing interest in the 20th century saw him regain popularity as a key witness to the art of his time, not only through his canvases, but also as the model chosen by the novelists Jean Lorrain and Marcel Proust, and through the anecdotes of his own life narrated by Edmond de Goncourt, Georges-Michel, and Montesquiou.

On 3 November 2018, a major retrospective opened for four months at the Musée Lambinet in Versailles, bringing together more than one hundred works by the painter as well as many documents.