Wolves thrashed Catalans Dragons on Saturday and they thought that they had got off the mark after three minutes when Kevin Penny went over, but the try was disallowed for interference after being sent upstairs.
That lead lasted just four minutes, however, as Warrington replied strongly and Jack Johnson was on the end of a sweeping move to go over for his 10th try of the season in the right corner to level things up.
Daryl Clark thought that he had put his side in front but Saints survived thanks to a knock-on call in their favour, but Wolves did go ahead after half an hour when Joel Monaghan added to his hat-trick against Dragons with his 145th try in 145 matches for the club.
The visitors were in the ascendancy and despite the hosts salvaging the ball just in front of their own posts, they lost possession downfield moments later and Chris Hill bulldozed through from 30 metres to extend the lead to 14-6 at half time.
Ryan Atkins twisted his way over nine minutes after the break to extend the lead, but St Helens launched a second-half revival as two tries in six minutes from Adam Swift and Mark Flanagan brought them to within four at 16-20.
Penny finally added a score of his own in the final minute to end the season in style for Wolves with a victory which leaves St Helens facing an away fixture in their Super 8s semi-final next week.