The deal also includes a player option for the 2027-28 season.
The 15-time All-Star has one season left on his current deal worth $54.7 million, but he will now earn $144.7 million over the next three years.
The Rockets brought in the 2013-14 MVP from the Phoenix Suns in a seven-team trade this summer.
Durant averaged 26.6 points, 6.0 rebounds and 4.2 assists while shooting 52.7% from the field and 43.0% from behind the arc for Phoenix last campaign.
He averages 27.2 points, 7.0 rebounds. 4.4 assists and 1.1 blocks, shooting 39.0% from three across his career.