Sosa donned the uniform of the Baltimore Orioles Wednesday after Commissioner Bud Selig approved his trade from the Chicago Cubs.
The Cubs dealt him for second baseman Jerry Hairston and two minor leaguers.
"I'll always love Chicago and I'm going to take Chicago in my heart," said Sosa. "I love you (Chicago), but you gotta move on. Now I'm here in Baltimore and this is my new house and I love it."
Although they sent the slugging superstar packing, the Cubs will still have to pay roughly $12 million of the $17 Sosa will earn in 2005.
Sosa failed to drive in 100 RBI for the first time in a decade during the 2004 campaign, but he was out of action for a month for a back injury.
"A lot people say my numbers were down, but I was hurt," Sosa said. "I was out for 40 games and I hit 35 home runs. I mean, come on."