Giants 4, Tigers 3 (10): NLCS MVP Marco Scutaro delivered a two-out RBI single in the top of the 10th inning and Sergio Romo struck out the side in the bottom half for his third save of the series as visiting San Francisco completed a four-game sweep and captured its seventh world championship.
Buster Posey belted a two-run homer and Brandon Belt added an RBI triple for the Giants, who won the World Series for the second time in three years.
Ryan Theriot led off the 10th with a single against Phil Coke (0-1) and moved to second on Brandon Crawford's sacrifice. After Angel Pagan struck out, Scutaro ripped a single to center field and Theriot easily beat Austin Jackson's throw to the plate, giving the Giants their third and final lead of the night.
Romo came on and struck out Jackson, pinch hitter Don Kelly and Miguel Cabrera, getting the Triple Crown winner looking with a fastball down the middle.
Santiago Casilla (1-0) picked up the win after recording the final out of the ninth inning.
San Francisco grabbed the lead in the second inning as Hunter Pence hit a one-out, ground-rule double and scored on Belt's triple off the wall in right field. Belt was stranded at third, as Max Scherzer retired Gregor Blanco and Theriot to avoid further damage.
After Scherzer induced a flyout by Posey with runners on the corners and two out in the third to keep the deficit at one, the Tigers took their first lead of the series in the bottom of the frame.
Jackson drew a one-out walk and advanced to second on a bunt groundout by Quintin Berry before Cabrera hit a shot to right that appeared to be helped into the seats by the wind, giving the slugger his first home run of the series and Detroit a 2-1 edge.
The Giants deflated the raucous crowd in the sixth, when Scutaro led off with an infield single and scored on Posey's one-out blast to left. The homer, which gave San Francisco a 3-2 advantage, was Posey's third of the postseason and first since his grand slam in Game Five of the NLDS against Cincinnati.
The lead was short-lived as ALCS MVP Delmon Young drilled Matt Cain's first offering over the wall in right for a two-out solo shot.
GAME NOTEBOOK: San Francisco won its final seven postseason games, outscoring the opposition 36-7. ... Detroit has lost seven consecutive World Series games dating back to 2006. ... Belt's RBI triple was his only hit of the series (1-for-13). ... Giants LHP Jeremy Affeldt pitched an impressive eighth inning. After walking leadoff hitter Avisail Garcia, Affeldt struck out Cabrera, Prince Fielder and Young. ... Coke answered in the top of the ninth by fanning Pence, Belt and Blanco. ... Tigers C Alex Avila was kept out of the starting lineup due to soreness in his right forearm. Avila was hit with a foul tip in Game One but was able to play in Game 3 on Saturday.