Kauto Star made history by becoming the first horse to win the King George VI Chase on four consecutive occasions.
The odds-on favourite was rarely troubled at Kempton Park, with Ruby Walsh riding the crowd favourite well clear of Madison du Berlais and Barbers Shop from the home turn.
With his latest victory Kauto Star went one better than Desert Orchid, who won the Kempton showpiece four times in five years between 1986 and 1991.
Trainer Paul Nicholls beamed: "I knew he was at his best and I can't believe how much he has improved. I don't think he has ever run better.
"He has got pace, he jumps and stays and is just a wonderful, wonderful horse."