The deal, made just before the deadline for playoff eligibility, gives the National League West-leading Diamondbacks a late-season spark plug with impressive October credentials.
"I'm definitely very excited with the opportunity to go out there and make the postseason," Eckstein, 33, said.
The 2006 World Series Most Valuable Player with the St. Louis Cardinals, Eckstein batted .277 with a homer and 23 RBIs in a part-time role for Toronto. Known for his all-out effort at 5 feet 7, he also helped the Angels win the 2002 World Series.
A two-time All-Star, Eckstein has a .333 average in 51 World Series at-bats with seven RBIs and nine runs.
A shortstop for nearly his entire big league career, Eckstein will play second base in Arizona, potentially sharing time with Augie Ojeda.
The Blue Jays received 23-year-old right-hander Chad Beck, who was 8-5 with a 3.67 ERA for two Single-A teams this year.
Dodgers: Second baseman Jeff Kent will undergo surgery to repair torn cartilage in his left knee tomorrow. Kent, 40, can begin rehabilitation soon after the operation and might return by the end of the season, manager Joe Torre said.
Indians-Rays: Cleveland sent minor league infielder Jorge Velandia to Tampa Bay for cash. Velandia was at Triple-A Buffalo after playing briefly for the Blue Jays and Indians earlier this year. Velandia played for Tampa Bay last year, batting .320 with two homers and 11 RBIs in 14 games.
Rockies: Colorado placed catcher Yorvit Torrealba on the 15-day disabled list because of a torn ligament in his left knee. To take his place on the roster, the Rockies purchased the contract of catcher Adam Melhuse from Triple-A Colorado Springs.