Irvin was suspended for the first four games of the season by the NFL for abusing their policy on performance-enhancing drugs.
Head coach Pete Carroll told reporters: "He's done really well. There's just a little rough around the edges on some stuff but he's in great shape and he's ready to go.
"He's really charged up and he's done a lot of studying over the time that he was out of here and has come back ready to take advantage of this.
"He doesn't want to wait another game or something to get going. We'd like to play him this week."
Seattle cut wide receiver Stephen Williams to make room for Irvin on their roster.