The NBA announced the decision Saturday after Cousins suffered a season-ending Achilles tear in Friday night's 115-113 win over the Houston Rockets.
George will suit up for LeBron James' team.
George, who entered Saturday's win over the Detroit Pistons averaging 20.9 points, 5.5 rebounds, 3.0 assists and 2.2 steals, was widely viewed as one of this year's biggest All-Star snubs when reserves were announced on Tuesday.
That was especially true in the eyes of Thunder point guard Russell Westbrook.
"Guy leads the league in steals, competes every night, top two at his position. Don't make any sense, regardless of anything else," Westbrook said Tuesday, per ESPN.com's Royce Young. "If you're going by All-Stars, there are certain All-Stars in this league. Everybody's not an All-Star. Just because you get voted in doesn't mean you're an All-Star. I just think it's outrageous. But you know, it is what it is."
Now that George is in—albeit under less-than-ideal circumstances—he will get to team up with Westbrook on LeBron's side.
According to the NBA's official release, which Bleacher Report's Howard Beck relayed, the head coach of James' team will choose Cousins' replacement in the starting lineup.
The coach of the Eastern Conference team with the best record through games played Feb. 4 will be appointed to lead James' squad. Boston Celtics head coach Brad Stevens isn't eligible because he represented the Eastern Conference at the 2017 All-Star Game.