Although the team did not disclose terms of the deal, the NFL Network's Ian Rapoport reported that Martin received a one-year contract to play for new Oakland coach Jon Gruden.
The Raiders also brought in a fullback Thursday, agreeing to terms with Keith Smith. ESPN's Adam Schefter reported the deal for Smith was two years and $4.2 million.
The 29-year-old Martin was released by the Tampa Bay Buccaneers on Feb. 20, ending his six-year tenure with the club.
A first-round pick of Tampa Bay in 2012, Martin rushed for a career-low 406 rushing yards last season and has been limited to 827 yards over the last two campaigns after erupting for 1,402 in 2015.
Martin burst on the scene as a rookie, rushing for 1,454 yards and amassing 12 total touchdowns. He added 49 receptions for 472 receiving yards, with all four totals serving as career highs.
After a pair of down seasons, Martin bounced back with a strong 2015 campaign, piling up 1,402 yards and seven total touchdowns. The Buccaneers responded by handing him a five-year, $37.75 million extension with $15 million in guaranteed money.
Martin received a four-game suspension for violating the NFL's performance-enhancing drug policy at the end of the 2016 season. He struggled to get going last season and was benched in favor of Peyton Barber in December.
In his career, Martin has 4,633 rushing yards and 1,091 receiving yards with 28 total touchdowns (26 rushing, two receiving).
Smith spent his first two seasons with the Dallas Cowboys at linebacker before he was shifted to fullback. He appeared in all 16 games in each of the past two seasons, rushing for 5 yards on two carries and catching eight balls for 46 yards.
Marshawn Lynch, who came out of retirement to join the Raiders, remains the team's No. 1 running back. However, it remains unclear whether Lynch will play in 2018.