Horvat was a regular member of the Australian national side, making 32 appearances between 1994 and 2002, and participated in a number of international competitions, including the 1987 FIFA U-16 World Championship, 1996 Summer Olympics, 1997 FIFA Confederations Cup, 2001 FIFA Confederations Cup and 2002 OFC Nations Cup. Horvat also played in the game with highest scoreline in an international football match, when Australia beat American Samoa 31–0.