Pujols rewrote the record books as he tied New York Yankees sluggers Babe Ruth, who accomplished the feat twice, in 1926 and 1928, and Reggie Jackson in 1977, as the only players to hammer three home runs in a World Series game.
The power-hitting Cardinals first baseman also tied the mark for most hits in a Fall Classic game (five), tied the record for most runs batted in (six), and set a new standard for most total bases off his hits (14).
The Cardinals erupted for 13 runs between the fourth and seventh innings to bury the Rangers with Pujols breaking out of an 0-for-6 World Series slump.
Texas had answered four runs by St. Louis in the fourth with three in their half of the inning, and matched the Cardinals' three runs in the fifth to make it 8-6, but the Redbirds scored four more runs in the sixth and two more in the seventh to turn it into a rout.
The starters from both teams, Kyle Lohse of St. Louis and Matt Harrison of Texas, were gone by the fourth.
St. Louis pulled away against hard-throwing Texas reliever Alexi Ogando, who had been brilliant for the Rangers in the American League Championship Series.
Coming on in the sixth with the score 8-6, Ogando gave up three hits, including a three-run home run by Pujols off a high fastball, and two walks in one-third of an inning with four runs crossing home.
The Cardinals stroked 15 hits and took advantage of six walks issued by Texas pitchers and three Rangers errors. Texas had 13 hits in the game and stranded eight baserunners.
Lance Lynn was credited with the win, while Harrison was charged with the loss.
Game Four of the Major League Baseball championship was later on Sunday with the Rangers sending Derek Holland to the mound against Edwin Jackson of the Cardinals.