Cincinnati sent Griffey, whose 608 career homers rank sixth on the all-time list, to the White Sox for right-hander Nick Masset, second baseman Danny Richar and cash considerations.
Boston dealt Ramirez, No. 23 on the career homers list with 510, to the Dodgers in a three-way deal that sent Pittsburgh left fielder Jason Bay to the Red Sox, while the Pirates acquired outfielder Brandon Moss and pitcher Craig Hansen from the Red Sox and third baseman Andy LaRoche and pitcher Bryan Morris from the Dodgers.
Seattle sent veteran left-handed reliever Arthur Rhodes to the Marlins for 22-year-old right-handed pitcher Gaby Hernandez in the only other Thursday trade.
Griffey learned of his being traded to the White Sox shortly after the Reds played the Astros on Wednesday night. Because of his no-trade clause, he had until 1 p.m. ET Thursday to approve of it, which he did sometime in the morning.
"They approached me yesterday afternoon," Reds general manager Walt Jocketty said of the White Sox. "We didn't have a lot of time to get it done so it tends to move a lot faster the last 24 hours. I was surprised. They obviously had a need for another bat in their lineup and a need for another outfielder. I know [White Sox GM] Kenny Williams had interest in Junior in the past and looked at this as a good opportunity to add him to his club."
After Reds owner Bob Castellini signed off, the proposal was brought to Griffey after the game in Houston.
"He was a little bit surprised maybe," Jocketty said. "He thought about it and said he wanted to talk to his family about it. I think it's a very good opportunity for him. they obviously wanted him, pursued him and came after him. That's got to be a good feeling for him I guess."
Teammate Jay Bruce said he and Griffey spoke briefly about the trade on Thursday morning.
"It was a lot more brief than I thought it was going to be," Bruce told MLB.com of their time as teammates. "It was kind of shocking. All of sudden, bam, it was done. He is still going to be a friend of mine. I'm upset that he's leaving but it's a good situation for him. He wants to win a ring. The White Sox are in first place and he has a chance."
Having joined the club before the 2000 season, Griffey was the longest tenured Red and hit 210 of his 608 career home runs with Cincinnati. The 38-year-old was off to a very slow start this season and batted .245 with 15 homers and 53 RBIs. But he ended his run with the Reds riding a 12-game hitting streak and hit a three-run homer in his final game against Houston.
Griffey is in the final season of a nine-year, $116.5 million contract that included a $16.5 million club option for 2009.
"He wasn't having his best year but he was just getting hot," Bruce said. "You won't be able to fill those shoes. No one is Ken Griffey Jr. It's the end of an era in Cincinnati. He got hurt a lot but was one of the top five best to ever step on the field."
Griffey's arrival in Chicago will give the White Sox two players with 500 or more home runs. Jim Thome is 16th with 526.
Where Griffey's left-handed bat will fit in the White Sox lineup remains to be seen. Griffey hasn't played center field since 2006 and the White Sox are set on the corners with Carlos Quentin in left and Jermaine Dye in right field. Thome is the club's primary designated hitter.
Ramirez's whirlwind week had him bound for Miami late Wednesday as part of a three-team deal, only to see those negotiations fall apart. In stepped the Dodgers, who secured the right-handed slugger to strengthen their bid to catch Arizona in the National League West Division race.
The Dodgers assumed Florida's vacated spot in the discussions with the Red Sox and Pirates.
Ramirez, the mercurial slugger who recently feuded with Red Sox management, signed an eight-year, $160 million contract with Boston as a free agent during the 2000-01 offseason. It includes club options in 2009 and 2010 at $20 million each. Ramirez received a $1 million relocation bonus for the trade. The Red Sox will reportedly pay the $7 million remaining on Ramirez's $20 million salary for this year.
"He's one of the best four or five hitters in baseball," Dodgers manager Joe Torre said on Wednesday. "I like him, yet he marches to his own drummer. I had him in the All-Star Game. It doesn't make sense to me [that he would be available]."
Ramirez was an American League All-Star in each of his eight seasons with Boston and he won two World Series rings with the Red Sox, in 2004 and 2007. He was the World Series Most Valuable Player in 2004, when the Red Sox won their first championship since 1918.
The 36-year-old left fielder is hitting .299 with 20 home runs and 68 RBIs this season. He has hit 510 home runs in his Major League career, spanning parts of 16 seasons, and is a career .312 hitter.
The Dodgers are now overloaded with outfielders with Ramirez joining Andruw Jones, Juan Pierre, Matt Kemp and Andre Ethier on the roster.
Bay, 29, is a two-time All-Star who is batting .282 with 20 homers and 64 RBIs. He posted career highs of 35 homers and 109 RBIs in 2006, his second All-Star season. He was the NL Rookie of the Year in 2004, when he hit .282 with 26 home runs the season after the Pirates acquired him in a trade that sent Brian Giles to San Diego.
Hansen, Moss and LaRoche will join the Pirates. Morris will report to Class A Hickory.
Hansen, 24, was Boston's first-round selection in the 2005 First-Year Player Draft out of St. John's University. Pitching primarily in middle relief, he has a 5.58 ERA in 32 games. He has a 6.15 ERA in 74 career Major League games.
Moss, also 24, had been used sparingly by the Red Sox. He is batting .295 with two homers and 11 RBIs in 78 at-bats.
LaRoche will join his brother Adam, the Pirates first baseman who is currently on the disabled list. Andy LaRoche was a 39th-round Draft pick in 2003. He batted .203 in 59 at-bats for the Dodgers this season.
The Marlins are hoping Rhodes, who has bounced back from Tommy John elbow reconstructive surgery, is the answer to the lefty relief role they have been seeking. In exchange the Mariners receive a prospect who could be a rotation candidate at some point.
Florida went 1-for-3 on the day. Their brief but intense flirtation with Manny over, the Marlins turned their attention to trying to address their bullpen and catching needs. They came up with the lefty reliever they had been seeking in Rhodes, but missed on the other two targets.
Marlins president of baseball operations Larry Beinfest would not give specifics or even confirm the Ramirez scenario.
"We had some things that we were looking at, that we were trying to improve, mainly with the 'pen, and we did that with Rhodes," Beinfest said. "We were trying to add catching depth, and we banged on I think every door. If we didn't, it's our fault. As far as any other opportunities, yes, there were other opportunities that we wanted to explore because we like to be active. With the minutes ticking, we wanted to take advantage of it. Why some of those things didn't come to fruition could be a number of factors. It could be the money, the players, to somebody else had different goals than we did."
The Rays, leading the AL East Division, were in on a number of targets, including Bay, but stood pat as the Deadline passed.
"We had conversations that went right down to the wire," said Andrew Friedman, Rays executive vice president of baseball operations. "And whenever you have that, obviously, you feel like there's a chance. But it takes two teams. And by definition trades are difficult to make. And we've worked extremely hard the last couple of weeks to try and find a pick and improve the team, but at the end of the day we didn't find something that lined up for us."
Friedman chose not to comment on how close the Rays got to making a deal for Bay or any other players.
"I'm not going to address speculation," Friedman said. "I know there was a lot out there. The way we view that is that the Trade Deadline is an opportunity for us to examine ways to improve our club. We did that. We had a lot of discussions. A few of them led right up to the Deadline. But obviously, nothing came to fruition."
Most of the other teams looking to make a deal at the Deadline also made no major changes.
"We exchanged proposals in a couple of instances but nothing to the point were I was calling [owner Tom Hicks] for the final signoff," Rangers GM Jon Daniels said.
Gerald Laird was back in the Rangers lineup on Thursday night, Jarrod Saltalamacchia was on the bench, Taylor Teagarden is with the United States Olympic team and Max Ramirez is still at Triple-A Oklahoma.
The Rangers were looking for young starting pitching in return and never received a sufficient offer for any of their catchers.
"That's fair to say," Daniels said.
Although left-handed reliever Ron Mahay and second baseman Mark Grudzielanek were among the Kansas City players rumored to be of interest, the Royals did not make a deal.
"The last four or five days, obviously, we've been in a lot of discussions and a lot of meetings and talked over a lot of different scenarios," GM Dayton Moore said, "but we were never real close to what I would call making a deal."
For most teams the Deadline passed quietly.
The Diamondbacks, Mets, Royals, Cardinals, Indians, Angels, A's, Astros, Orioles, Twins, Tigers, Angels, Phillies, Nationals, Braves, Cubs, Brewers, Rockies, Giants and Padres did not trade on Thursday.
Jim Molony is a reporter for MLB.com. MLB.com reporters contributed to this report. This story was not subject to the approval of Major League Baseball or its clubs.