Kimmel joked that "Oscar," the statuette, is the embodiment of the Times Up movement because it keeps its hands where you can see them and lacks genitals.
"He's literally the statue of limitations," Kimmel said.
He encouraged stars to speak from the heart -- but be brief during their acceptance speeches.
Kimmel started his monologue diving straight into material about last year's infamous best-picture mistake.
"I do want to mention, this year, when you hear your name called, don't get up right away," said Kimmel. "Give us a minute."
More seriously, Kimmel went on to talk about several political movements making change in the entertainment industry and across the country.
"I hope you will listen to many brave and outspoken supporters of movements like #MeToo, Times Up and never again because what they're doing is important. Things are changing for the better, they are making sure of that. It is positive change," he said.
Kimmel mention disgraced film mogul Harvey Weinstein, saying he deserved to be kicked out of the academy - one of only two people to ever be expelled.
He noted Greta Gerwig's best director nomination, the first female director to be nominated in several years, but said there's still a long way to go, especially when it comes to equal pay.
He followed with the scandal between actress Michelle Williams and actor Mark Wahlberg, who was paid over a $1 million more than his costar for the film "All the Money in the World." He added that Wahlberg later donated his earnings to the Times Up Legal Defense Fund and joked to Michelle, "What are you going to do with those 80 bucks?"
Adding some lightheartedness to the Hollywood harassment scandal, Kimmel talked about the love story in the best picture nomination "The Shape of Water," saying men have screwed up so badly in the past year that "women started dating fish."
In apparent earnestness, Kimmel encouraged the night's Oscar winners to "speak from the heart, remind people of equal rights and join students of the Parkland, Florida school shooting at the March for Our Rights gun control rally later this month; however, he jokingly asked that celebrities keep their speeches short, blaming the show's reputation for running long.
As a reward, Kimmel said the person with the shortest speech would win an $18,000 Jet Ski, which was presented by Oscar-winning actress Helen Mirren.