The two free agents will replace cornerback Pete Hunter (knee) and tight end Dan Campbell (foot), who both suffered season-ending injuries in Monday night's 21-18 win at Washington and need surgery.
The 31-year-old Williams gives Coach Bill Parcells some veteran experience in the secondary. The loss of Hunter had left him with three rookies -- fourth-round pick Bruce Thornton and seventh-round picks Jacques Reeves and Nate Jones -- playing alongside second-year corner Terence Newman.
Williams is a nine-year veteran who won a Super Bowl with Green Bay in his rookie year (1996) and played 111 of 112 possible games in his seven years there. In six years as the Packers' starting right corner, he totaled 445 tackles and 19 interceptions.
The New York Jets released Ricks, 29, during the pre-season.
He has 155 career receptions for 1,939 yards and eight touchdowns. He has also played for San Diego, Kansas City and Detroit.