He made the announcement through a release from the University of Texas, where he won the Heisman Trophy in 1998.
Williams, 34, was a first-round pick by the New Orleans Saints in 1999 and played for the Miami Dolphins for eight seasons. He was with the Baltimore Ravens last season.
It was in a Ravens game Jan. 1 that Williams passed the 10,000-yard mark. He was the 26th player to reach that level.
Williams finished with 10,009 yards and 66 rushing touchdowns to go with 342 receptions for 2,606 yards and eight touchdowns in 147 NFL games. He was a Pro Bowl selection in 2002, his first season with Miami.
He was famously drafted by New Orleans after the Saints traded all six of their draft choices in 1999 to move into position to take Williams. Williams was a 1,000-yard rusher twice for New Orleans and led the NFL with 1,853 yards for Miami in 2002.
He rushed for another 1,353 yards in 2003 but then retired. He returned rather than give back bonus payments but was suspended for the 2006 season because of a fourth NFL drug policy violation.
Williams played that season for the Toronto Argonauts of the CFL. He returned to the NFL and had one more 1,000-yard season (1,127 in 2007).