The loose-forward was expected to be out for up to eight weeks after a collision with an advertising hoarding ended his participation in Sunday's defeat to Wakefield.
Initial concerns were the 24-year-old had broken his wrist in two places and faced a lengthy spell on the sidelines during a key part of Hull's campaign.
However, after allowing the inflammation in his wrist to settle down, Westerman has had the injury assessed again and no break has been found following scans.
The news is a welcome relief for coach Lee Radford, with Westerman one of Hull's stand-out players this season.
The Black and Whites can ill-afford to lose a key figure in their side as they enter a difficult run of games, starting with the arrival of Wigan to the KC Stadium on Friday night.
Westerman could well feature for Hull against the Warriors in what would be a remarkable turnaround, although the Mail understands the Magic Weekend derby is a more realistic target with his wrist still sore and swollen.
Hull will be without second-row Chris Tuson for Friday's game, however.
The ex-Wigan man will miss a reunion with his former employers after suffering a hamstring injury against the Wildcats.
Tuson has already missed games this season with a hamstring tear, but his latest injury is not a repeat of the previous problem.
