The 28-year-old has played a big part in Stoke's success after sealing a permanent deal from Real Zaragoza in January following a loan spell.
Kemp said: "Jermaine has been very impressive since he came here. He is playing the best football of his career and is a big part of what we do.
"He is a quality player. He produces crosses for us, he makes goals, he keeps the ball and scores goals as well. Not only that his work-rate has been tremendous."