He was a principal dancer of Diaghilev's Ballets Russes until 1914, but Diaghilev fired him when he got married with Romola de Pulszky. He stopped dancing around 1919, and became crazy.
He was the brother of Bronislava Nijinska .
Note: the French spelling for his name usually is "Nijinski", the English one usually is "Nijinsky". Both spellings can occur in these pages...

A statue of Nijinski by Rodin (made in 1912, Rodin attended
the premiere of L'après-midi d'un Faune).

Nijinsky at the premiere
of L'après-midi d'un Faune (with Lydia Nelidova).