In his debut for the Thunder in their season opener on October 19, 2017, George scored a team-high 28 points in a 105–84 win over the New York Knicks. On November 10, 2017, he scored a season-high 42 points in a 120–111 win over the Los Angeles Clippers. He made 13 of 22 shots and had nine rebounds and seven assists. After starting the season with an 8–12 record, the Thunder improved to 20–15 with a 124–107 win over the Toronto Raptors on December 27. George scored 33 points against the Raptors and went 7 of 10 from 3-point range, tying the Thunder record for 3-pointers in a game. On January 20, 2018, he had a 36-point effort in a 148–124 win over the Cleveland Cavaliers. On January 27, 2018, George was named as a replacement for the injured DeMarcus Cousins on Team LeBron for the 2018 NBA All-Star Game. On February 1, 2018, he scored a season-high 43 points in a 127–124 loss to the Denver Nuggets. In the Thunder's regular season finale on April 11, 2018, George scored 40 points in a 137–123 win over the Memphis Grizzlies. He went 13 of 20 from the field, including eight of 14 3-pointers. In Game 1 of the Thunder's first-round playoff series against the Utah Jazz, George scored 36 points in a 116–108 win. He set an Oklahoma City playoff record with eight 3-pointers, making eight of 11 shots from long range, and 13 of 20 shots overall. In Game 4, George scored a team-high 32 points in a 113–96 loss. In Game 5, George recorded 34 points and eight rebounds, as the Thunder rallied from 25 points down in the second half to fight off elimination and beat the Jazz 107–99. The Thunder went on to lose Game 6 to bow out of the playoffs with a 4–2 defeat; George had a game-high eight assists in Game 6, but scored just five points on 2-of-16 shooting.