"Climate change is real", DiCaprio said. "This win is also an important opportunity to bring more attention to climate change and action needs to be taken by all of us right now".
In one of the evening's few surprises, Mark Rylance won best supporting actor for playing an undercover Soviet agent in Steven Spielberg's "Bridge of Spies".
"Mad Mad: Fury Road" won four honors in the early going: costume design, production design, makeup and film editing.
CUTEST SELFIE.In the audience, Oscar nominee Brie Larson uses her phone to snap a photo of herself and 9-year-old co-star Jacob Tremblay of "Room".
Racial themes and barbs about the selection of an all-white acting nominee line-up for a second year were a running theme of the show, dubbed "the white People's Choice awards" by Rock, an outspoken black comedian.
Even on Sunday night at the awards ceremony, DiCaprio himself didn't seem to expect to hear that he had finally (finally!) gotten a nod from the Academy when Julianne Moore announced he'd won the big prize.
We say goodbye and R.I.P.to those much loved Leo Oscar memes. Leonardo DiCaprio (finally) wins coveted Oscar After six nominations for unbelievable performances, Leo finally took home the gold because of his role in The Revenant. "If they nominated hosts, I wouldn't even get this job", Rock quipped.
With this win, Inarritu has entered the history books, becoming the first director since 1950 to bag the best director trophy two years in a row.
Adam McKay and Charles Randolph took best adapted screenplay for their self-described "trauma-dy" about the mortgage meltdown of 2008, The Big Short.
Talk of election was largely absent from the ceremony, though Vice President Joe Biden was met by a standing ovation before talking about sexual assault on college campuses in an introduction to best-song nominee Lady Gaga.
Alejandro Iñárritu, who won Best Director a year ago for "Birdman, " did indeed become only the third director ever to put together back-to-back wins in that category, the first since Joseph L. Mankiewicz managed that way back in 1951. The Hungarian movie Son of Saul, a harrowing Holocaust drama, won the Oscar for best foreign language film.
Later, Rock said, "We want opportunity". Last year's telecast, hosted by Neil Patrick Harris, slid 16 percent to 36.6 million viewers, a six-year low.
This is the second win for Sharmeen, who previously bagged the Oscar in the same category in 2011 for "S aving Face", a documentary about an acid attack victim.
Some celebrities were attending an event in Flint, Michigan, #JusticeForFlint.