The Dropkick Murphys were scheduled to play six club dates in Boston around St. Patrick’s Day. Coronavirus ended that plan.

Instead, the Celtic-influenced punk band played a single show on a soundstage March 17 and streamed it online. In place of the 10,000 or so people who could have attended the gigs, 10 million fans tuned in.

“We had always talked about streaming the Boston shows but never got around to it,” said bassist and singer Ken Casey. “On 48 hours’ notice we had a full rock concert going.”

Concert tours provide the bulk of musical artists’ income. Before the pandemic essentially froze the live-concert business, PricewaterhouseCoopers projected live music events would generate $28.8 billion in revenue in 2020. Now artists are putting their performances online—and hoping fans and dollars follow.

Artists like Taylor Swift have used live streams in the past to promote new music or videos. As droves of fans stream online concerts in this era of social distancing, many in the industry say they are setting the stage for artists to earn money through sponsorships, advertising and merchandise.

YouTube plans to introduce features in the coming weeks to help artists earn more money from these live streams, according to people familiar with the matter, including memberships to artist channels where fans can pay for early or exclusive access to content and virtual meet-and-greets. YouTube is also expanding paid-commenting features used by influencers to musical artists, those people say.

Vivendi SA’s Universal Music Group, the largest of the three global music companies, is lending equipment to artists and helping them stream live performances. Universal is trying out a “studio in a box,” delivering audio, visual and lighting equipment to artists and providing engineering support to help with setup. The company has also developed a streaming and e-commerce platform that artists can use to perform, engage with fans and share content across YouTube, Facebook and other social networks. The company doesn’t take a direct cut from the platform’s use, but can benefit indirectly from royalties and sponsorships.

Her North American theater tour postponed, Tinashe is among the artists going online. The R&B singer said she had long been interested in streaming her live shows to fans, and the present moment became the perfect time to try it out.

Using her own audio equipment, with her brother manning the lights and cameras on loan from a streaming company, Tinashe worked through a one-hour set from a corner of her home in Los Angeles last month, complete with a backup dancer (at a social distance) and costume changes.

Simulcast across an app, website and social-media accounts maintained by LiveXLive—the company that produced the show—as well as Tinashe’s own social-media accounts, the free set drew over 157,000 viewers. The singer followed a set list for the first half, then took viewer requests for the second.

“We don’t get the same energy we do from a crowd when we’re physically in the same room,” she said. “But it was amazing how much you’re still able to, knowing people were watching.”

Startups have tried for years to build businesses around virtual concerts, betting on virtual reality and other technologies. The electronic music producer Marshmello drew millions of fans for a “live” set inside the videogame Fortnite last year—a stunt that worked, analysts said, because those fans were already on Fortnite’s platform.

Now, virtual performances are seemingly everywhere, and most are free or presented as fundraisers for coronavirus-relief efforts. Bandsintown, a site where fans can see if their favorite artists are playing nearby, has rejiggered to track live streams, and is now promoting 2,000 such shows daily.

“Live streaming and video consumption in general was always going to break through and become more mainstream,” said Celine Joshua, Universal’s head of commercial content and artist strategy. “We’ve only reached that point faster.”

After plans to perform at Coachella this month and then tour the U.S. fell through, British alternative rocker YungBlud took to YouTube to live stream a show with guests Machine Gun Kelly, Bella Thorne and Oliver Tree.

The hourlong video has racked up over 600,000 views. Superfans can buy a $65 T-shirt emblazoned with the words “A livestream concert from YungBlud on March 16.” Last Thursday YungBlud added a second live show, which also generates ad revenue on YouTube.

Live streams are also creating sponsorship opportunities. Jessie Reyez, signed to Universal’s Island Records, recently streamed a low-tech live performance to promote her new album. She used a hairbrush as a make-believe microphone, and a bottle of Jameson whiskey, the brand sponsoring the show, sat on a shelf behind her.

Proceeds from YungBlud’s and Ms. Reyez’s online performances were donated to charities.

Mr. Casey, of the Dropkick Murphys, said he prefers performing live, in front of the band’s famously rowdy fans. Nonetheless, after the St. Patrick’s Day show, fans who had watched the stream with their children inundated the band with videos, photos and messages.

“We may have gotten a whole new generation of fans,” Mr. Casey said.