"It all feels incredibly surreal," he told reporters backstage of the online push for him to win. "It's surreal because you can't reach out and physically meet everybody. You hear it on the Internet, you hear it from other people and the truth is, we always strive for the best of what we do and this year in particular I've been overwhelmed with such support."
The actor added that he's filled with gratitude.
DiCaprio also said that he was thrilled to get the opportunity to highlight global warming.
"Making 'The Revenant' was about man's relationship to the natural world...climate change is real," he said in his acceptance speech. "It is happening right now. It is the most urgent threat facing our entire species and we need to work collectively together and stop procrastinating."
The actor concluded his speech by saying, "I do not take this night for granted."
"The Revenant" led in Oscar nominations this year with 12. Director Alejandro González Iñárritu also took home an award Sunday.
DiCaprio, 41, has already racked up tons of awards for the role in which he portrays the real-life frontiersman Hugh Glass, who was attacked by a bear then left in the wilderness, trekking about 200 miles to find the men who deserted him.
When DiCaprio's nomination was announced in January, the actor was gracious.
"I am so grateful to the Academy for their recognition of this film. Making 'The Revenant' was one of the most rewarding and collaborative experiences of my life," he said in a statement. "None of this would have been possible without Alejandro's talent, vision and determination. Our dedicated crew also deserves to share in this moment. Together, they have created a truly unique cinematic experience. Congratulations to all of my fellow nominees this season. Thank you to the Academy."