Crouch had been on the pitch nine minutes when he pounced to turn in the rebound after England goalkeeper Joe Hart spilled a shot from Xherdan Shaqiri.
But another substitute would yet have a decisive impact on the result, Carroll superbly turning in a cross from Aaron Cresswell to ensure the spoils were shared at London Stadium on Tuesday.
A run of four straight losses had seen Stoke's position appear increasingly perilous, the Potters in danger of slipping out of the Premier League after a 10-year top-flight stay.
Crouch had appeared to claim the role of hero with a goal that made him Stoke's record Premier League marksman, but Paul Lambert's men are on the brink after Carroll's leveller.
Stoke remains 19th in the table, five points adrift of safety with four matches remaining, one of which is against UEFA Champions League semi-finalists Liverpool at Anfield, while West Ham - which saw three goals ruled out - is seven clear of the drop zone.