Pop superstar Taylor Swift -- who had been silent about the election -- posted a picture of herself on Instagram dressed casually as she waited in a long line at a polling station.
Although Swift -- who performed at the 2008 Republican convention but generally stays out of politics -- encouraged voters to come to the polls, she did not reveal her own choice.
Katy Perry, often seen as Swift's rival, is Clinton's self-described "number one fan." On Election Day, she posted repeatedly on Twitter, where she has nearly 94 million followers, more than anyone else.
In one video, Perry appears with a fluffy little dog asking voters to head the polls.
She also posted a commercial for Clinton set to "Roar," in which a diverse array of Americans sway to her blockbuster tune, urging a "vote against hate."
Perry also waded into politics in her home state of California by supporting a proposition that would fully legalize marijuana. She linked to an opinion piece by rap mogul Jay Z, who argued that the failed US "war on drugs" has disproportionately targeted minorities.
Jay Z and his wife, pop diva Beyonce, led a concert for Clinton on Friday in the battleground state of Ohio. Beyonce on Tuesday posted a short, cinematic video from the show to her 88 million Instagram followers.
"So many people lost their lives for us to even have the opportunity to vote," Jay Z said at the end of the video.
It would be a "major disservice if we don't go out and let our voice be heard," he added.
Rihanna also declared her Election Day support for Clinton, tweeting a selfie with a picture of the candidate on the chart-topping singer's shirt, whose new dreadlocks dangled down.
And Colombian superstar Shakira reached out to US Latino voters, who have been particularly offended by Republican candidate Donald Trump's fiery calls to curb immigration.
"The Latino vote can help decide the fate of a nation and the world's," she tweeted in English, adding, "Don't stand still -- vote now!"
Trump, who enlisted few celebrity supporters, criticized Clinton for appearing with Jay Z and Beyonce, pointing to the rapper's use of profanity.
Trump nevertheless campaigned with hard rocker Ted Nugent, who grabbed his own genitals to illustrate his view of Democrats.