After playing for the Texas Rangers and Chicago White Sox, Sosa joined the Cubs in 1992 and became regarded as one of the game's best hitters.

Sosa hit his 400th home run in his 1,354th game and his 5,273rd at-bat, reaching this milestone quicker than any player in National League history.

[1] In 1998, Sosa, along with Mark McGwire, achieved international fame for his home run-hitting prowess in pursuit of Roger Maris' single-season home-run record.

Though born in a Batey community in Consuelo,[3] his officially registered birthplace is San Pedro de Macorís, which was "the largest town nearby".

"[5] Sosa made his major league debut on June 16, 1989, with the Texas Rangers, wearing #17 and leading off as the starting left fielder.

[6] On July 29, 1989, the Rangers traded Sosa with Wilson Álvarez and Scott Fletcher to the Chicago White Sox for Harold Baines and Fred Manrique.

The White Sox traded Sosa and Ken Patterson to the Chicago Cubs for outfielder George Bell before the 1992 season.

However, he did not lead the league in any of those seasons; in 2001, he finished behind Barry Bonds, who hit 73 homers, breaking the single-season home run record set by McGwire in 1998 (70).

On June 3, 2003, Sosa was ejected from a Chicago Cubs-Tampa Bay Devil Rays game in the first inning when umpires discovered he had been using a corked bat.

[15] Sosa finished the season with 40 home runs and hit two more in the 2003 NLCS against the Florida Marlins, falling to the team in seven games.

In May 2004, Sosa suffered an odd injury while sitting next to his locker chatting with reporters before a game in San Diego's Petco Park.

[19] On January 28, 2005, the Cubs traded Sosa to the Baltimore Orioles in exchange for infielder-outfielder Jerry Hairston Jr., infielder Mike Fontenot, and RHP Dave Crouthers.

To facilitate the deal, Sosa and his agent agreed to waive the clause that guaranteed his 2006 salary, and the players' union indicated it would not object to that agreement.

"[20] During that year, Sosa accompanied President Leonel Fernández of the Dominican Republic on several diplomatic trips including to the United States, Japan, and Taiwan.

The contract included an invitation to spring training, where Sosa competed for a spot in the lineup with Nelson Cruz, Jason Botts, and other rookies/prospects.

He has also homered in The Ballpark at Disney's Wide World of Sports, near Orlando, Florida, a usually minor-league and Spring training park that hosted a regular season series between the Rangers and the Tampa Bay Devil Rays in May 2007, although he did not hit a homer at the two regular season games the Cubs played at the Tokyo Dome in 2000 vs. the Mets.

Sosa became only the fifth man in history, following Babe Ruth, Willie Mays, Hank Aaron, and Barry Bonds, to hit 600 regular season home runs.

On May 28, 2008, Sosa announced that he instructed his agent not to offer his services to any MLB team for the 2008 season, and planned on filing for retirement, but never did.

[25] On December 25, 2008, Sosa announced he intended to unretire and play in the World Baseball Classic and once again test the free agent market in hopes of signing with a Major League ballclub in 2009.

Sosa said that he had been keeping in shape at his home, and was hoping that after a strong World Baseball Classic he would prove to major-league teams that he was still capable of playing in MLB.

He made the announcement in the Dominican Republic and said that he was calmly looking forward to his induction into the Baseball Hall of Fame since his statistics were up to par.

[26] On June 16, 2009, The New York Times reported that Sosa was on a list of players who had tested positive for performance-enhancing drugs in 2003, in baseball's steroids scandal.

The paper stated that this information had been obtained from unnamed attorneys with knowledge of Major League Baseball drug test results from 2003.

[27] Previously, Sosa sat alongside Rafael Palmeiro, Jose Canseco, and Mark McGwire at a hearing before the United States Congress.

"[29] On December 19, 2024, Sosa released a somewhat ambiguous public statement through his PR firm, stating, "There were times I did whatever I could to recover from injuries in an effort to keep my strength up to perform over 162 games.

No one played harder or wanted to win more…We plan on inviting him to the 2025 Cubs Convention and, while it is short notice, we hope that he can attend.

The buzz around this drastic change prompted him to go on a Spanish-language television station to deny that he was ill, or that he hated being dark-skinned, or that his new skin tone was the result of steroid use.