Striker Ricardo Fuller scored his first hat-trick for Stoke as West Brom surrendered top spot.
He took just five minutes to open the scoring after good link-up play with strike partner Mamady Sidibe.
Fuller then ghosted in unmarked to lash home Liam Lawrence's free-kick seven minutes before half-time and notched a third just after the hour.
Roman Bednar pulled one back for Albion but it could not stop Stoke extending their unbeaten run to seven games.
Stoke's hat-trick hero Ricardo Fuller:
"The fans were absolutely great. They made such a noise and really helped us through the game.
"To be fair they have been great all through the season, and for them to have a team doing so well, that's what they deserve.
"There is a great atmosphere in the dressing room and we believe we can do whatever we want this season."
West Brom boss Tony Mowbray: "In Ricardo Fuller they've got a hot striker who is in form and gave us a few problems today.
"We played against a decent strikeforce and the quality they've got up front was evident.
"I enjoyed watching our team for long spells in the second half and yet we didn't take our chances."
Stoke: Simonsen, Wilkinson, Shawcross, Cort, Pugh, Lawrence, Eustace, Delap, Cresswell, Sidibe (Dickinson 84), Fuller (Parkin 90).
Subs Not Used: Hoult, Zakuani, Pulis.
Goals: Fuller 5, 38, 66.
West Brom: Kiely, Hoefkens, Cesar (Albrechtsen 68), Pele, Robinson, Gera, Greening, Koren, Filipe Teixeira (Phillips 46), Brunt (Miller 46), Bednar.
Subs Not Used: Steele, Morrison.
Booked: Brunt, Cesar.
Goals: Bednar 72.
Ref: Mark Halsey (Lancashire).
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