It was the second multiplayer trade in less than 48 hours for the Marlins, who have begun a July fire sale after disappointing through the first four months of this season.
A three-time All-Star and former National League batting champion, Ramirez expressed mixed emotions over being dealt from the Marlins, where he has spent the first seven years of his career.
"For me this day is not easy. The Marlins have been my family, the only one I had in baseball," Ramirez told ESPNdeportesLosAngeles.com's Enrique Rojas. "I will never forget who gave me that first opportunity that every human being needs. They will always be in my heart."
Ramirez made his Dodgers' debut in St. Louis on Wednesday night. Wearing No. 13, he was at third base and batted fifth. Ramirez finished 2 for 4, including a triple, and an RBI in the Dodgers' 3-2 loss to St. Louis in 12 innings.
Ramirez, 28, is a former NL Rookie of the Year and led big league shortstops with 124 home runs and a .521 slugging percentage from 2006 through 2010.
"He meant a lot to this organization, a premium talent, an uber talent in a lot of respects," Marlins president of baseball operations Larry Beinfest said.
But Ramirez has been a major disappointment over the past two seasons. He moved to third base this past winter to accommodate free-agent addition Jose Reyes but is batting just .246 with a .752 OPS for the Marlins.
"I leave with some regret, not having helped bring a championship to Miami," Ramirez said. "But otherwise, I just keep positive memories of my time with the team."
"It's sad to see Hanley go to another team," Reyes added. "We developed a great relationship. I feel he was one of my real good friends on the team. Any time someone close to you goes to another team, it kind of surprises you a little bit and you get sad a little bit."
The Dodgers are hoping Ramirez will be reinvigorated by a change of scenery and give them another run producer to complement Matt Kemp and Andre Ethier in the batting order. The Dodgers rank 12th in the NL with 379 runs scored and are 13th in OPS at .684.
Said Dodgers coach Manny Mota: "We will work with Hanley to help him recover the confidence he lost. We know that he is young and immature, but will work with him to make him feel comfortable and help him develop all the potential he has to play baseball."
Dodgers general manager Ned Colletti said his team first heard from one of its scouts that the Marlins might be open to moving some players a couple of days ago, but discussions with the Marlins didn't escalate until late Tuesday night. The Dodgers were able to speak with Ramirez before the trade was consummated to gauge his feelings about returning to shortstop while Dee Gordon is on the disabled list, but then potentially moving back to third base afterward.
Manager Don Mattingly said Ramirez will return to his old position as soon as he is comfortable with a switch.
"Hanley's willing to play anywhere that helps the team win," Mattingly said. "It's not a situation that really concerns us right now."
Ramirez took ground balls at shortstop before Wednesday's game but played third base.
Ramirez is making $15 million in the fourth year of a six-year, $70 million contract. He's scheduled to make $15.5 million in 2013 and $16 million in 2014.
"Everything that happens in life is because of God's plan, and perhaps the plan for me is that things are better in Los Angeles and for the Marlins without me," Ramirez said.
The Dodgers haven't gotten much production from their third basemen, with Juan Uribe batting just .190 with two homers and 17 RBIs and others doing little at the spot.
Los Angeles is 2½ games behind NL West-leading San Francisco. After a 32-15 start, the Dodgers are just 21-30 since.
The Marlins recently decided to try to unload several veteran players and big salaries in the midst of a disappointing season. The Ramirez deal comes less than two days after Miami traded pitcher Anibal Sanchez and infielder Omar Infante to the Detroit Tigers.
"We weren't winning with the group we had, and we want to make changes," Beinfest said.
The trade marks a marked departure for Colletti and the Dodgers, who have operated with a restricted payroll in recent years under previous owner Frank McCourt. They are now operating without a set payroll, according to new Dodgers president Stan Kasten.
"It is different," Colletti said. "It's kind of liberating and freeing that we're able to make a baseball trade. We found a player that we really liked that we feel can add to our lineup and at the same time show the guys who have been busting their tail for the last three months that we acknowledge how hard they've played and want to give them the support we can.
"This move was in the wind. Whether it's Mark Walter or Peter Guber or any of the other Guggenheim folks, or Magic Johnson or Stan Kasten. There's no doubt what they're here for and there's no doubt what they visualize this organization doing and being. It's a freeing feeling to be able to do business like that."
Colletti said the Dodgers remain in the hunt for starting pitching and another bat up until the trade deadline.
"The hunt isn't over," he said.
In their colorful new uniforms, the Marlins were 31-23 through June 23, just percentage points out of first place, then lost 17 of their next 20 games. They started Wednesday 45-52, fourth in the NL East and 12½ games out of first place.
"These are tough trades, but when you underachieve at the level this team has underachieved and has not won at the level we expected it to -- we have talked about restructuring, and this is part of it," Beinfest said.
The Marlins are weighing offers for ace Josh Johnson, according to ESPN The Magazine's Buster Olney, in an attempt to further shave payroll. Miami also could deal struggling closer Heath Bell in advance of next week's trade deadline, according to ESPN.com's Jerry Crasnick.
Choate, a 36-year-old left-hander, is 0-0 with one save and a 2.49 ERA in 44 games. He began his big league career with the New York Yankees in 2000 and has pitched for Arizona and Tampa Bay.
Eovaldi, a 22-year-old righty, is 1-6 with a 4.15 ERA. He made his major league debut last season.
ESPN.com's Jerry Crasnick, ESPNLosAngeles.com's Ramona Shelburne and The Associated Press contributed to this report.