The Spurs didn't disclose terms of the deal, but Mason's agent, Mark Bartelstein, told The Associated Press on Thursday that Mason signed a two-year contract for "just a little less than" $8 million. On Thursday, Bartelstein said the team had come to an agreement with Mason.
Mason spent the last two seasons with the Washington Wizards. Last season, the 6-foot-5 guard averaged a career-high 9.1 points and 1.7 assists in 80 games.
Mason said Friday he's happy to be in Texas.
"It seems like they win championships every other year," Mason said. "Next season's 08-09 so I guess they're due, and hopefully I can be a big part of it."
The Spurs won titles in 1999, 2003, 2005 and 2007. Last season they lost to the Los Angeles Lakers in the Western Conference finals.
"You look at the history, these guys are in, I guess I [should] say, we, are in the hunt every year," Mason said. "Every time you think of San Antonio you think of a title contender."
Last season Mason played in a reserve role for all but nine games. He picked up additional playing time because of Gilbert Arenas' knee injury.
He was drafted by the Chicago Bulls with the 31st pick in the 2002 draft, but appeared in just 43 games with the Bulls and Toronto Raptors in his first two seasons. Before joining the Wizards, Mason played professionally overseas for two seasons. In his first season with the Wizards, he averaged 2.7 points.
Mason had a shoulder injury that required surgery early in his career.
"I feel like my career is just starting," the 27-year-old Mason said. "This was my first year with consistent playing time in my career."
Spurs general manager R.C. Buford said Mason has a strong overall game, and praised his 3-point shooting and defense. Mason shot .398 from beyond the arc last season.
"He's been a guy that our coaches have had on their radar for a long time," Buford said. "We tried to get something done last year and to Roger's credit he went out and proved to us that he deserved a much bigger opportunity than we talked about last year."