Andrea Bargnani had 19 points off the bench for Toronto (2-0), while Jose Calderon had 16 points and 13 assists. Jamario Moon added 11 for the Raptors.
Al Harrington led Golden State (0-2) with 26 points, adding 11 rebounds, while Stephen Jackson finished with 19 points. Andris Biedrins had 17 points and 13 rebounds for the Warriors.
Corey Maggette, who led Golden State with 27 points in a season-opening loss to New Orleans, was held to 14, while Kelenna Azubuike came off the bench to score 15.
Jackson, who played all 48 minutes in the season opener, ended up playing 44 on Friday, fouling out in the final minute of overtime.
Toronto trailed by two with 14.5 seconds left in regulation when Bosh made two free throws to tie it at 96-96.
After letting the clock run down to 5 seconds, Maggette turned the ball over as he drove to the basket, giving the Raptors the ball with 0.7 seconds left in regulation. Bargnani inbounded to Parker, who got a shot off, but it rimmed out, sending the game to overtime.
Parker made two steals on the first two possessions of overtime as Toronto scored eight consecutive points to secure the win and improve to 7-3 in home openers.
Jermaine O'Neal shot 2-for-10 and finished with five points and six rebounds, but made three blocks. O'Neal fell to the floor after blocking a second-quarter shot by Brandon Wright, wagged his finger while still on his back, then got up and said "No way" to the Golden State bench as he ran up the court.
Toronto led 51-50 at the half.
Notes:@ Golden State picked up the third-year options on guard Marco Belinelli and Wright, and declined the fourth-year option on guard Marcus Williams. ... Each of Toronto's first five baskets was scored by a different member of the starting lineup. ... Bosh delivered a brief pre-game address to fans, thanking them for their support.