A source told ESPN's Michael Smith on Tuesday that the terms of the deal call for Walker to receive a six-year, $55 million contract that includes more than $16 million in guarantees and pays him roughly $27 million over the first three years of the deal.
The Raiders also announced the signing of free-agent offensive tackle Kwame Harris on Wednesday. Oakland also has renegotiated running back Dominic Rhodes' contract this week, securing his return for next season. Rhodes was due a $2 million roster bonus on Friday, but agreed to restructure his deal.
Soon after being released, at least a third of the league reached out to Walker, a six-year veteran.
Injuries limited Walker to eight games last season and he finished with 26 catches for 287 yards and no touchdowns.
He started the season with two 100-yard games before missing two months following a third knee operation.
Beginning his career with the Packers, Walker played two seasons in Denver. He had 69 catches for 1,084 yards and eight TDs the first season. But the offseason was punctuated by tragedy. Involved in a drive-by shooting soon after the season ended, teammate Darrent Williams died in Walker's arms.
The signings fill positions of need for the Raiders, who are trying to build their offense around quarterback JaMarcus Russell, the first overall pick in last year's draft.
After losing receiver Jerry Porter to Jacksonville through free agency, the Raiders had only one wide receiver under contract with more than six career catches.
Walker was supplanted by Brandon Marshall as the Broncos' top receiver and was released so Denver could avoid paying him a $5.4 million option bonus.
Walker tore a knee ligament that wiped out most of his 2005 season in Green Bay,
Walker made the Pro Bowl with the Packers in 2004 after catching 89 passes for 1,382 yards and 12 touchdowns. He has 252 career catches for 3,815 yards and 30 scores.
Ronald Curry led the Raiders with 55 receptions for 717 yards last season, but had only 11 catches in the final five games last season. Curry has 174 career receptions for 2,166 yards and 11 touchdowns.
The other receivers under contract are Johnnie Lee Higgins, who had six catches as a rookie last season for 47 yards, Will Buchanon, who has one career reception, and
Drisan James and Todd Watkins, who have never caught a pass in the NFL.
Harris, a first-round pick by San Francisco in 2003, started all 32 games in 2005-06 for the 49ers before being relegated to a backup role last season. Harris has been plagued by penalty problems throughout his career, but Oakland is hoping line coach Tom Cable can resurrect him.
Michael Smith covers the NFL for ESPN. Information from The Associated Press was used in this report.