[9] Sculthorpe moved to St Helens in 1997 for £375,000,[10] at the time a record transfer fee for a forward (based on increases in average earnings, this would be approximately £516,500 in 2013).

[11] In the 1997 post season, Sculthorpe was selected to play for Great Britain at loose forward in all three matches of the Super League Test series against Australia.

Having won the 1999 Championship, St. Helens contested in the 2000 World Club Challenge against National Rugby League Premiers Melbourne Storm, with Sculthorpe playing as a loose forward in the loss.

He also played for St Helens at loose forward and kicked a drop goal in their 2000 Super League Grand Final victory over Wigan.

Having won Super League VI, St Helens contested the 2003 World Club Challenge against 2002 NRL Premiers Sydney Roosters.

Sculthorpe was named St Helens captain in 2004, and led the team to victory over Wigan in the 2004 Challenge Cup Final at the Millennium Stadium, Cardiff.

[citation needed]He was named as Great Britain captain in 2005, although injury ruled out for the most of 2005's Super League X and prevented him from leading the side in the 2005 Tri-Nations tournament.

After being injury hit in 2008's Super League XIII with only a handful of games played, St. Helens announced they would release Sculthorpe at the end of the season.