The deal, which also includes a swap of 2013 draft picks, gives the Tigers a likely solution to their season-long problems at second base and adds another experienced arm to their starting rotation.
The trade underscores Detroit's desire to win now after signing slugger Prince Fielder in the offseason. Turner was considered the Tigers' top pitching prospect and earned his first major league win Sunday.
"We gave up a lot," Detroit general manager Dave Dombrowski said. "It hurts to do what we did."
Miami also receives catcher Rob Brantley and left-hander Brian Flynn in the deal.
Detroit is coming off a three-game sweep of Chicago that propelled them into first place in the AL Central. The Tigers lead the White Sox by 1½ games, but it took them a while to come around following a first-half funk. Detroit has used Ryan Raburn (.172 average), Ramon Santiago (.216) and Danny Worth (.215) at second base.
Now Infante arrives after hitting .287 with 10 stolen bases for the Marlins this year. It's his second tour of duty with Detroit. He played there from 2002-07 before the Tigers traded him.
"I am happy to go to Detroit," Infante said through a translator. "I know Detroit, they are in first place. I am happy to go back and hopefully do good there."
The 28-year-old Sanchez was 5-7 with a 3.94 ERA for Miami this year. Sanchez threw a no-hitter at 22 and has shown flashes of the ability that had him touted as a top young talent. But he's had trouble staying healthy over a full season and has won more than 10 games only twice in his seven big league seasons.
"It's a new era for me, a new opportunity for a new team," Sanchez said. "I'm so glad for the opportunity to be with the Marlins for a while."
The Tigers designated minor league left-hander Kelvin De La Cruz for assignment.
Detroit is loading up for the stretch run, hoping to win a second straight division title.
"We are sending them to a fun place," Marlins president Larry Beinfest said. "They're in first place, we wish we were and we're not, and we needed to realize that."
Turner is 1-1 with an 8.03 ERA this year, but his stock remained high after he contributed a solid start Sunday in a win over the White Sox. He's expected to report to Triple-A New Orleans, but might not be there for long.
"Jacob Turner is very well known throughout the game, one of the top prospects," Beinfest said. "We've known about him for quite some time and watched him of late. This is a tough get, to get a major league-ready starter is probably the toughest thing to acquire in the game."
Dombrowski said the Tigers could afford to trade Turner because of some other young pitchers in their organization. Drew Smyly is 4-3 with a 4.42 ERA with Detroit this year, although he's out now with a strained muscle in his right side. Left-hander Casey Crosby also made three starts this year for the Tigers.
"We do have a little bit of depth in that area," Dombrowski said.
Sanchez moves into the rotation spot filled by Smyly and Turner. Wade LeBlanc may start in Sanchez's spot for Miami.
It's a difficult trade for the Marlins, who added star shortstop Jose Reyes, starting pitcher Mark Buehrle and closer Heath Bell in the offseason and are playing in a new ballpark. Miami was 44-51 entering Monday night's game.
"We're disappointed in the club's performance," Beinfest said. "We made our moves this winter, came out of spring training, and everyone's expectations, and rightfully so, that we'd be in a different position today. The current team is really not in contention, at a tenuous spot at best, and I think it was time to restructure."
Detroit, meanwhile, has played better lately, and that gave Dombrowski a chance to zero in on a couple specific needs instead of having to overhaul the roster.
"We felt all along that we had a club that was a good club," he said. "What you hope to do is identify a specific position or two."
The teams are also trading competitive balance lottery picks. Detroit receives one between next year's first and second rounds from Miami, while the Marlins get one between rounds two and three from the Tigers. It's the first time baseball draft picks have been traded, which is allowable on a limited basis under the new collective bargaining agreement.