Kolb took over for the injured John Skelton during a drive late in the fourth quarter with the Cardinals trailing 16-13. He responded by connecting on 6-for-8 passes for 66 yards, capping the march with a 6-yard TD pass to Roberts with 5 minutes remaining.
Skelton left with a right ankle injury after going 14-of-28 for 149 yards and an interception.
Roberts made five grabs for 54 yards for the Cardinals (1-0).
Seattle (0-1) was led by rookie quarterback Russell Wilson, who gained 153 yards with a touchdown and an interception on 18-of-34 passing.