Boldin was injured in Sunday's 34-13 loss to Dallas, when he made three receptions for 69 yards, including a 44-yard touchdown reception in the second quarter.
"Just hearing the word 'bruise' was a sigh of relief," Boldin told the Arizona Republic.
Boldin, 25, a second-round draft pick out of Florida State in 2003, missed six games last season after surgery to repair a slight ligament tear in his right knee.
In seven games this season, he has 39 receptions for 616 yards and three touchdowns.
Also on Wednesday, Cardinals Coach Dennis Green announced that Kurt Warner will be the starting quarterback Sunday against Seattle. He has been out since the first contest against the Seahawks since Sept. 25.