In an open letter promoting a fundraiser that the 54-year-old actor and his wife, Amal Clooney, are holding for Clinton on April 16 at their Los Angeles home, Clooney manages to bash presidential hopeful Donald Trump without actually saying his name.
"If you listen to the loudest voices out there today, you'd think we're a country that hates Mexicans, hates Muslims, and thinks that committing war crimes is the best way to make America great again," Clooney writes, calling out Trump's campaign slogan. "The truth is that the only thing that would prevent America from being great would be to empower these voices."
He then went on to praise Clinton for being a "voice of tolerance and experience."
"As this primary process continues, Hillary could soon have an insurmountable delegate lead and with that, the Democratic nomination. That would then make her the only grown-up in the room," he writes. "And if ever there was a time for a grown-up, that time is now."
This isn't the first time Clooney has made his thoughts on Trump known. In an interview with the Guardian earlier this month, he called the controversial politician a "xenophobic fascist."
"He's just an opportunist," he said. "Now he's a fascist; a xenophobic fascist."
However, he was confident that Trump would not be elected president.
"Let's put things into perspective," he said. "You know, the truth of the matter is, in election season, things go crazy, and the loudest voices are the furthest and most extreme. So you hear a massively stupid idea, like we're going to ban Muslims from the country. Now, we're not ever going to do that."
"It says in the Statue of Liberty, bring us your huddled masses," he added. "It's not what's going to happen."
Tickets to Clinton's fundraiser cost $33,400 per person, CNN reports, but supporters can enter his contest for two free tickets simply by signing up, and giving the requested $10 donation.
"The good news is, I'm not cooking," Clooney jokes in the letter.
The Hollywood star isn't the only celebrity who's publicly endorsing Clinton for president. Fellow supporters include Beyonce, Katy Perry, Kim Kardashian West, Kanye West, Khloe Kardashian, Lena Dunham, Steve Harvey, and Snoop Dogg, just to name a few.
Of course, not everyone is a fan -- Caitlyn Jenner has slammed Clinton on her E! show, I Am Cait, and is an advocate for Ted Cruz.
"If we're unfortunate enough to get Hillary as our next president, we need her on side," Jenner said on the I Am Cait season two premiere, speaking to a group mainly made up of members of the trans community and vocal activists. "Although she won't be. She couldn't care less about women. She cares about herself."
"I would never, ever, ever vote for Hillary," she clarified on another episode. "We're done. If Hillary were to become president, the country is over."