The Canadian club has been outscored 21-8 this season and its nine-match losing streak to start the 2012 campaign was an MLS record. Suriname-born Winter, 45, was 7-22 with 15 drawn at Toronto, winning only one away match.
Mariner began his playing career with Plymouth Argyle in 1973 before Sir Bobby Robson signed him for Ipswich Town in 1976. He scored 96 goals in 260 matches before departing in 1984 and was Man of the Match in the 1978 FA Cup Final, which Ipswich Town won 1-0 over Arsenal.
Mariner, who had been serving as Toronto's director of player development, also played at Arsenal and Portsmouth and in the United States and Malta before retiring in 1993. As a coach, Mariner served as an assistant with the New England Revolution before joining Toronto FC.
Winter was a standout for for Ajax of Amsterdam and played for Lazio and Inter Milan in Italy before retiring as a player in 2003.