Justin Bieber donated $545,000 to AIDS/HIV research this week.

The 20-year-old singer, who is "trying to be a better person" after several brushes with the law in recent months, reportedly shocked his fellow VIP guests, including Leonardo DiCaprio, when he made the generous pledge at the amfAR's 21st Cinema Against AIDS Gala in Antibes, France, on Thursday night.

A source told gossip website TMZ.com that the "Heartbreaker" hitmaker "stunned" the star-studded crowd, which also included Heidi Klum, John Travolta and Sharon Stone, when he quietly agreed to match another wealthy guest's pledge of more than half a million dollars.

Organizers asked the Canadian star if he was serious about donating such a large amount of money and he quietly said yes, explaining that he felt very inspired to do something good.

The Wolf of Wall Street star Leonardo, 39, also raised $1 million at the event by auctioning off a trip to space with him in 2015.

A source previously said that Justin, who was arrested and charged with Driving Under the Influence (DUI), resisting arrest and possessing an invalid driver's licence earlier this year in Miami, is determined to get his life back on track. "He's making more of an effort to hang out with people who are positive influences in his life," the insider said.