This was his fifth acting nomination at the Oscars, but the long overdue win might have been made even sweeter because of the wait. ET was with Leonardo on the red carpet of his first Oscars in 1994, when he was nominated for his supporting role in What's Eating Gilbert Grape at just 19.
"Being nominated against these people is like being with the top heavyweights," Leonardo said at the time. The award ultimately went to Tommy Lee Jones that year for The Fugitive.
While his mom was his biggest advocate on the night, a close second was his Titanic co-star Kate Winslet. When they greeted each other on the red carpet, you could still feel their chemistry almost 20 years after starring in the movie that made them both household names.
"I just asked him if he was OK," Winslet told ET. "Then actually I noticed that he had one little eyebrow off, so I just put it back into place for him."