Actor Joaquin Phoenix is making good on his recent promise to be more mindful of the environment.

The "Joker" star, who won the Golden Globe for best actor in a dramatic film on Sunday night, will wear one tuxedo throughout awards season, according to designer Stella McCartney.

McCartney tweeted that she is "proud to join forces" with the actor for the pursuit.

"This man is a winner… wearing custom Stella because he chooses to make choices for the future of the planet," she wrote. "He has also chosen to wear this same Tux for the entire award season to reduce waste."

Phoenix, 45, kicked off his acceptance speech by thanking the Hollywood Foreign Press Association for serving a vegan meal during the ceremony and "for recognizing and acknowledging the link between animal agriculture and climate change." He then pleaded with his fellow actors to do what they could to limit their carbon footprints.

PHOTO: Joaquin Phoenix, winner of the award for best performance by an actor in a motion picture drama for "Joker," arrives at the InStyle and Warner Bros. Golden Globes afterparty at the Beverly Hilton Hotel, Jan. 5, 2020, in Beverly Hills, Calif.
Richard Shotwell/Invision/AP
Joaquin Phoenix, winner of the award for best performance by an actor in a motion picture drama for "Joker," arrives at the InStyle and Warner Bros. Golden Globes afterparty at the Beverly Hilton Hotel, Jan. 5, 2020, in Beverly Hills, Calif.

"It's great to vote, but sometimes we have to take that responsibility on ourselves and make changes and sacrifices in our own lives, and I hope that we can do that," he said during his acceptance speech. "We don't have to take private jets to Palm Springs for the awards sometimes or back. Please. And I'll try to do better and I hope you will too."