How many teams have won the World Series at home?

Only once. In the 1993 World Series, Joe Carter's three-run homer in the bottom of the ninth inning gave the Toronto Blue Jays an 8-6 win over the Philadelphia Phillies and the world championship in six games. The only other home run to end a World Series happened in a Game 7 -- Bill Mazeroski's memorable 1960 home run against the New York Yankees that gave the Pittsburgh Pirates a title.