Artest, who played for the Houston Rockets last season, received a five-year deal worth about $33 million, according to his agent, David Bauman.
Seated next to Lakers general manager Mitch Kupchak, Artest professed that he has wanted to be a Laker for several years, but the timing was never right.
"This was a long time coming," Artest said. "As I started to compete against the Lakers and against Kobe [Bryant], I had respect for him and I always wanted to be a teammate of his."
During the playoffs, Artest could be seen courtside at Lakers games and was in attendance during the NBA Finals last season, when Los Angeles lost to Boston. After the Celtics clinched the championship in Game 6, Artest approached Bryant in the locker room and told him he wanted to help him out.
"I just wanted to make that connection," Artest said. "I wanted to let him know that he played tough and he played great and I can't wait to be a teammate of his."
Artest agreed to a deal last week, but couldn't sign it until Wednesday. The Lakers also re-signed guard Shannon Brown.
Brown signed a two-year contract for $4.2 million. The Lakers are still trying to retain free agent forward Lamar Odom, who averaged 12.3 points and 9.1 rebounds during the playoffs.
Kupchak said he has been in constant contact with Odom's agent, Jeff Schwartz.
"We talk several times a day and I'm hopeful that something can be worked out," Kupchak said. "I really can't be any more optimistic than that."
Kupchak said he had no reservations about signing the colorful and enigmatic Artest, since he has stayed out of trouble for the last few years.
Artest is best remembered for charging into the stands when he played for the Indiana Pacers and allegedly punching a fan after a beer was thrown at him in the closing minute of the team's game against the Detroit Pistons, causing a melee in 2004.
"I think if you would watch the way he's conducted himself on the court the last several years, you would feel the same way I feel," Kupchak said. "We've all been in situations we may have done something we regret, but I think if you don't do it again and you learn from it and you demonstrate that you've learned, then I think that's enough."
In 10 seasons with Chicago, Indiana, Sacramento and Houston, Artest has averaged 16.1 points, 5.1 rebounds and 3.2 assists. The 2004 defensive player of the year believes he will improve the Lakers on that end.
"I'm still able to stay in front of guys and I'll have some shot blockers [behind me]," said Artest, referring to Pau Gasol and Andrew Bynum. "When you've got two 7-footers and hopefully Lamar Odom, all these guys behind you, I can just get into my man defensively and they're going to have to adjust their shot."
Bryant has said he's not sure the Lakers are a better team with Artest, who agreed with the assessment.
"It's not a given that just because you add me to the team we're going to be the No. 1 team," Artest said. "You've got to put that work in.
"That's something that I'm not afraid to do."
Artest will wear No. 37 next season, a number a fan suggested to help him honor Michael Jackson. Jackson's "Thriller" album was the No. 1 record for 37 straight weeks.
Artest called deferring to Bryant a "no-brainer" because his goal is to win a championship.
"Kobe has four rings, I've got none," Artest said. "I've got to have one; I need one bad."