Sammy (4/22) claimed two crucial wickets in his first two deliveries before adding two more later to play a big role in Sunrisers defending 150 for seven they scored revolving around Parthiv Patel's 61 after being put into bat at PCA Stadium.
Dale Steyn chipped in with two wickets for 20 runs while Thisara Perera grabbed on wicket.
Chasing 151 for a win, KXIP were restricted to 120 for nine with Luke Pomersbach top-scoring with a 40-ball 33 not out. The KXIP, who are now virtually out of reckoning for a play-offs berth after today's loss, were to blame themselves as they allowed the Sunrisers to recover from 52 for five at one stage.
In their run chase also, the home side were on course in the first half of their innings but lost the plot in the second half.
After today's win, the Sunrisers occupy the fifth spot with 16 points from 13 matches while KXIP remained on sixth place with 10 points from 13 matches.
Fast bowler Dale Steyn gave the Sunrisers breakthrough in the first over itself by removing opener Mandeep Singh for a duck with the batsman failing to connect an out-swinging delivery properly to get a leading edge for Cameron White to take a low diving catch.
The other opener and KXIP captain Adam Gilchrist and Shaun Marsh denied success to the Sunrisers bowlers for a while. Marsh hit Steyn for two fours in the third over before Gilchrist meted out Ishant Sharma the same treatment in the sixth over.
Gilchrist (26) and Marsh (18) looked like settling down for big knocks before Sammy removed both the batsmen in his first two deliveries in the eighth over to change the complexion of the game.