Chasing 152 for win, KKR lost early wickets but Suryakumar Yadav (43 not out) and Yusuf Pathan (21) stitched a 38-run sixth-wicket partnership to help them achieve the target in 19.4 overs and set a domestic record of 12 straight wins.
Earlier electing to bat, Scorchers rode Adam Voges' unbeaten 71 to post 151 for seven in 20 overs as KKR off-spin ace Sunil Narine (4-31) and left-arm chinaman Kuldeep Yadav (3-24), who got the Man of the Match award, succeeded in containing the Australian Big Bash champions from getting a big score.
Robin Uthappa (23) did try to hang around but was caught behind after trying to chase a rising delivery off Nathan Coulter-Nile (2-41).
Manish Pandey (24) also tried to give some stability to the innings but fell to a perfect Coulter-Nile yorker in the 11th over.
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Dutch star Ryan ten Doeschate, who had a big role to play in the opening win against Chenni Super Kings, couldn't last long either as he fell to Yasir Arafat (3-39) and put KKR in a bit of trouble at 87 for five.
But Suryakumar, whose 19-ball knock was laced by a four and 4 sixes, ensured that KKR register their third successive win in the tournament so far even after Andre Russell (4) was cleaned by Arafat on the first ball of the last over. PTI SJR FK
In the Perth innings, openers Simmons (39) and Voges gave the team a perfect start after smashing 68 runs in 9 overs.
The batsmen though got a little help from the fielders as Kallis (0-39) dropped a caught and bowled chance in the second over to give Voges a life on 2 runs.
Simmons got another life on 27 after Suryakumar Yadav dropped a running catch at deep mid-wicket off Piyush Chawla (0-35).
But the left-handed opener could not capitalise on the lives given to him as Kuldeep (3-23) gave KKR their first breakthrough on the last ball of the ninth over after getting Simmons stumped.
Kuldeep once again delivered a punch in the 12th over after getting Mitchell Marsh stumped for 4.
But Voges carried on in the same vein, as Gambhir kept rotating his bowlers to try and keep the batsmen unsettled.
The Voges-Whiteman duo stitched a third-wicket 39-run partnership to improve the teams' run rate, moving into the final overs.
Narine though soon plotted Whiteman's downfall after the left-hander hit the off-spinner for a four and a six in the 16th over but another slog on the last ball cost him his wicket as Suryakumar took a safe catch at long-on.
Kuldeep also kept the wicket-taking going as the 18-year-old player packed Coulter-Nile back for a duck to check Perth's scoring rate.
The champion West Indian bowler did not get a hat-trick but once again showed his might in the shorter format after giving away just 7 runs and getting the wicket of Yasir Arafat (10).