The four took part in YouTube's Dear Class of 2020 stream Sunday, along with Lady Gaga, BTS, Lizzo, Taylor Swift, Jennifer Lopez, Justin Timberlake, Mariah Carey, Dan Levy and the Schitt's Creek cast, and other stars.
In a commencement speech, Beyoncé celebrated students' resilience amid such challenges as the coronavirus (COVID-19) pandemic and George Floyd's death. Floyd, a 46-year-old black man, died May 25 in Minneapolis, Minn., while being restrained by a police officer who knelt on his neck.
"You have arrived here in the middle of a global crisis, a racial pandemic, and worldwide expression of outrage at the senseless killing of yet another unarmed black human being, and you still made it," Beyoncé said.
"We're so proud of you. Thank you for using your collective voice and letting the world know that black lives matter," she added.
Michelle Obama also addressed "prejudice and inequality" in another speech. She assured grads they are not alone as they struggle with the weight of current events.
"So, if any of you are scared, or confused, or angry, or just plain overwhelmed by it all, if you feel like you're searching for a lifeline just to steady yourself, you are not alone. I am feeling all of that, too. I think we all are," she said.
Obama encouraged grads to lead with integrity and empathy as they go forth in the world.
"I hope that what you're going through right now can be your wakeup call. That it pushes you not just to think about what kind of career you want to build, but what kind of person you want to be," the former first lady said.
"And that leads me to my second lesson. In an uncertain world, time-tested values like honesty and integrity, empathy and compassion -- that's the only real currency in life," she added. "Treating people right will never, ever fail you."
Perry concluded the special by leading graduates in a ceremonial tassel turn. The singer, who is pregnant with her first child with Orlando Bloom, performed a medley of songs, including her new single "Daisies."
Dear Class of 2020 was initially scheduled to stream Saturday but was postponed to Sunday out of respect for a memorial service for Floyd held Saturday in Raeford, N.C.