The 49ers signed the free agent running back to a one-year deal Monday, giving Westbrook the second chance he's been seeking in recent months. The St. Louis Rams, Dallas Cowboys and Washington Redskins were other teams considering Westbrook, who ultimately said his decision wasn't all about money at this stage.
A league source told ESPN NFL Insider Adam Schefter that Westbrook's deal is worth $1.25 million guaranteed, with $1.25 million worth of incentives.
San Francisco finished 8-8 last season and will settle for nothing less than reaching the playoffs this year and ending a seven-year postseason drought.
"My No. 1 concern throughout the process was going to a winning team, a football team that was coached by a man I respect and a team that had a winning tradition and players that would be able to achieve that," Westbrook said when formally introduced Monday night. "I think I found all of those things here in San Francisco. It was a long process but in the end I think it turned out well for me."
Coach Mike Singletary made things perfectly clear with his would-be player: Frank Gore is the Niners' No. 1 back. And that is unlikely to change.
That's fine with Westbrook, who still believes he can be an every-down back but that his banged-up body in recent seasons might be a sign he's better suited to take on a lesser role now.
"Frank's the man," Westbrook said. "He's done tremendous things in the past, Pro Bowls, talented guy, I've respected his game from afar. In Philly, I watched and studied him a whole lot. I'm going to go out there and push him as much as I can, help him as much as I can and I'm sure he'll do the same for me to make me better. Of course he'll be the starter but I'll be the guy right behind him pushing him. Any chance I get, to go out there and make plays."
Westbrook, who turns 31 on Sept. 2, was released by the Philadelphia Eagles in February after an injury-filled 2009 season. He had been looking for a new team ever since, talking to several coaches from various franchises.
"When I talked to Brian Westbrook, I just wanted him to know how much I respected him as a player. The fact that he's still there at this point, I'm just thankful that he was an option," Singletary. "The more we talked and the possibility of that being able to work out, it was great. But the thing I wanted him to know about our team and about Frank: 'Frank Gore is the guy. Frank Gore is our running back. I don't want to lie to you and have you think something different and when you get here it's like wait a minute, I could have gone somewhere else.'"
Westbrook has rushed for 5,995 yards and 37 touchdowns on 1,308 carries in eight NFL seasons all with the Eagles and also caught 426 passes for 3,790 yards and 29 TDs.
Westbrook knows it will take him a little time to get acclimated to a new playbook.
The Niners had a void to fill after Glen Coffee, Gore's backup, abruptly announced he was leaving football after one NFL season.
While Singletary had high hopes for Coffee's career, he is thrilled to get a veteran with Westbrook's resume.
"It's a very young offense. We've got a lot of tools, young guys," Singletary said. "I think he really adds a lot of value in terms of the leadership, the experience, having been a part of good football teams. That adds a lot to our team on the offensive side of the ball."
Westbrook led the NFL with 2,104 yards from scrimmage in 2007, but missed eight games last season with a pair of concussions and an ankle injury while scoring only two touchdowns.
He insists doctors have told him he's good to go and Westbrook doesn't fear taking another hard hit. Yet he welcomes a fresh start with the Niners.
"I am fully healthy. In my mind, last year was a tough season for me," he said. "I spent the whole offseason rehabbing, I didn't have time to prepare for the season so I kind of went into the season blind without any preparation at all. So it was a tough year. I was playing catch up the entire season and obviously wasn't able to do that. This year, I've been able to spend my whole offseason preparing for a football season. Now that my body is completely healthy, I'm ready to go out there and perform."
TE Vernon Davis (strained right knee) was listed as day to day to return. "Whatever he needs," Singletary said of Davis' timetable. "He looks good, looks strong." ... LB Travis LaBoy, who sustained a concussion the first week, was cleared to practice Tuesday. Fellow LB Ahmad Brooks could begin biking and possibly also running this week as he recovers from a lacerated kidney that he injured Aug. 6. ... Second-team CB Will James will miss 4 to 6 weeks with a sprained ankle, while rookie returner Kyle Williams sprained a big toe and will be evaluated in several weeks. ... New C David Baas showed Singletary enough in Sunday's 37-17 exhibition win over the Colts that he is penciled in as the starter for now. It had previously been considered a competition with Tony Wragge and Cody Wallace.
Information from The Associated Press contributed to this report.