Born in the Oryol province of Russia, Andreyev originally studied law in Moscow and Saint Petersburg, but abandoned his unremunerative law practice to pursue a literary career. He became police-court reporter for a Moscow daily, performing the routine of his humble calling without attracting any particular attention. His first story published was About a Poor Student, a narrative based upon his own experiences. It was not, however, until Gorky discovered him by stories appearing in the Moscow Courier and elsewhere that Andreyev's literary career really began.

From that day to his death, he was one of the most prolific writers in Russia, producing short stories, sketches, dramas, etc., in frequent succession. His first collection of stories appeared in 1901, and sold a quarter-million copies in short time. He was hailed as a new star in Russia, where his name soon became the trend. In 1902, he published "In the Fog" and "The Abyss". These two stories caused great commotion because of their candid and audicious treatment of sex. His two best known stories may be "The Red Laugh" (1904) and "The Seven Who Were Hanged" (1908). His dramas include the Symbolist plays The Life of Man (1906), Tsar Hunger (1907), Black Masks (1908), Anathema (1909), and He Who Gets Slapped (1915).. The Life of Man was staged by both Stanislavski (with his Moscow Art Theatre) and Meyerhold (in Saint Petersburg), the two main highlights of Russian theatre of the twentieth century, in 1907. Andreyev's best work was from the evocation of absolute pessimism and a depairing mood. Moreover, he began losing fame as his novels became more and more sensational.

Aside from his political writings, Andreyev published little after 1914. In 1916, he became the editor for the literary section of the newspaper "Russian Will." He later supported the February Revolution, but he foresaw Bolsheviks coming into power as catastrophic. In 1917, He moved to Finland. From his house in Finland he addressed manifestos to the world at large against the excesses of the Bolsheviks. Idealist and rebel, Andreyev spent his last years in bitter poverty, and his premature death from heart failure may have been hastened by his anguish over the results of the Bolshevik Revolution. His last novel was Satan's Diary, but he died before he finished it. It was still published even though it embodies evil triumphs

A play, The Sorrows of Belgium, was written at the beginning of the War to celebrate the heroism of the Belgians against the invading German army. It was produced in the United States, as were the plays, The Life of Man (1917), The Rape of the Sabine Women (1922), He Who Gets Slapped (1922), and Anathema (1923). A popular and acclaimed film version of He Who Gets Slapped was produced by MGM Studios in 1924.

Poor Murderer, an adaptation of his short story Thought made by Pavel Kohout, opened on Broadway in 1976.He was married to Countess Wielhorska, a niece of Taras Shevchenko. Their son was Daniil Andreyev, a poet and mystic, author of Roza Mira.

Leonid Andreyev's granddaughter, the American writer Olga Andrejew Carlisle, published a collection of his short stories, Visions, in 1987.