The two-hour "One World:Together at Home" event, broadcast across multiple television channels in the United States and overseas, featured a Who's Who of pop culture in the biggest celebrity gathering so far to mark the effects of the virus.
Contributions, all filmed in their homes, also came from Elton John, Jennifer Lopez, Stevie Wonder, British soccer star David Beckham, former US first ladies Michelle Obama and Laura Bush, Andrea Bocelli, Celine Dion, Billie Eilish, Bill Gates and dozens of others.
"I'm so grateful for the healthcare workers, the medical workers, all the grocery store workers and delivery people, the postal workers, all the other nonprofits that are working so hard," said Gaga, who helped organize the event.
The event, led by the World Health Organization (WHO) and the nonprofit group Global Citizen, told the personal stories of teachers and healthcare, grocery, delivery, postal and other workers.
It showed social media postings and news clips of doctors and nurses being applauded by communities around the world, deserted world landmarks, families greeting each other through windows, and acts of kindness in support of those who are isolated and frail.
"We aren't asking for money tonight," said Stephen Colbert who hosted the broadcast alongside his US late night television rivals Jimmy Kimmel and Jimmy Fallon.
Instead of seeking public funds, the event encouraged philanthropists and companies to contribute to the WHO's COVID-19 Solidarity Response Fund. Corporate and other donors have already contributed some $150 million, organizers said.
What I'd like tonight, if I can, is to give you the permission for the moment to... 'Smile'," said Gaga, kicking off the evening by launching into a version of the ballad made famous by Nat King Cole.
Beyonce did not perform but sent a video message in which she noted the disproportionately high death rates from COVID-19 in the black community.
"This virus is killing black people at an alarming rate in America," she said, urging viewers to protect themselves.
Swift, on piano, gave an emotional rendition of her ballad "Soon You'll Get Better," which was originally written during her mother's battle with cancer.
The Rolling Stones, filmed in four separate locations, sang "You Can't Always Get What You Want," with Mick Jagger and Keith Richards playing acoustic guitars.
"We all appreciate the healthcare workers but never like now," Winfrey said in a video message. "They truly are the best of us... We need to ensure that governments step up now and provide healthcare workers with the equipment and the funds they need."
Wonder played the late Bill Wither's classic "Lean on Me," while McCartney, recalling that his mother was a nurse and midwife, sang "Lady Madonna."
Earlier on Saturday, pop, classical and rap musicians from the United States, Asia and the Middle East took part in a six-hour livestream that featured Latin star Luis Fonsi, R&B singer Jennifer Hudson, Chinese singers Eason Chan and Jacky Cheung, India's Vishal Mishra and Emirati musician Hussain Al Jassmi.
Celebrities called on people to stay at home, wash their hands regularly, practice social distancing and put pressure on their political leaders to introduce widespread testing for the disease.