The wardrobe change came in the final seconds of the first half during the Mavericks' 106-98 win on Tuesday at American Airlines Center in Dallas.
Doncic's squad led 58-56 with about six seconds remaining in the frame when the rookie dribbled the ball up the left flank. He crossed half court before firing up a one-handed heave. The 3-point attempt found only air, falling to the floor as the buzzer sounded.
Doncic turned back toward around before pulling his jersey over his face. He then took his hands and pulled it apart, splitting the script Dallas and his No. 77 right down the middle.
"I was just pissed," Doncic told reporters. "I didn't play good. I was frustrated."
The No. 3 overall pick in the 2018 NBA Draft was awarded with the Western Conference Rookie of the Month award for December during the win.
Doncic scored 17 points and had seven rebounds and six assists in the win. Harrison Barnes led the Mavericks with 20 points. DeAndre Jordan picked up 13 points, 16 rebounds, four assists and four blocks in the win.
Patrick Beverley scored 16 points and had nine rebounds and three assists for Los Angeles.
Doncic, 19, also received a $10,000 fine on Tuesday for kicking a basketball into the stands during a game against the Indiana Pacers on Saturday at Bankers Life Fieldhouse in Indianapolis.
He is averaging 19.9 points, 6.8 rebounds, 5.3 assists and 1.2 steals per game during his rookie campaign.
The Mavericks host the Detroit Pistons at 8:30 p.m. on Friday in Dallas.