A spokeswoman for Sunderland said: "The club has negotiated with Varga, whose contract was originally due to expire in 2004.
"Both parties have agreed to the termination of his contract with immediate effect.
"Sunderland would like to wish Stan all the very best for his future."
Varga joined the Black Cats for £875,000 in July 2000 but has made just 30 appearances for the club.