Last month, Ryan Jones, a small-business owner in San Francisco, found himself making an unexpected plea to fellow merchants.

San Francisco Pride was in trouble and needed their help.

Mr. Jones’s business, a bakery called Hot Cookie, had never given money to the annual festival that celebrates L.G.B.T.Q. life. But when he heard that major companies like Comcast and Anheuser-Busch were not renewing their sponsorships, leaving a funding gap of more than $1 million, he felt compelled to act.

“I asked myself what I can do to support,” Mr. Jones said of the festival, which will be held June 28-29. One answer: He and his business partner pledged to donate 5 percent of sales from the bakery’s most popular cookies to this year’s event. Another: He would try to get other local businesses to do something similar.

Across the country, Pride events are struggling. Big corporations have been withdrawing funding for the festivals, part of a retreat from diversity initiatives that has increased under the second Trump administration. In response, local businesses are helping to make up some of the shortfall. Many see it as a way of standing up not only for L.G.B.T.Q. people, but also for what the annual celebration means for their local economies.

In San Francisco, Pride is a multimillion-dollar festival drawing hundreds of thousands of visitors, dozens of musical acts and hundreds of food vendors. The event, in turn, has become a powerful economic engine, bringing in an estimated $350 million in 2015, the last time the city conducted a study of its economic impact. Now, many local businesses, including hotels, restaurants, bars and retailers, are concerned about what it would mean if the festival had to be scaled back.

Hot Cookie, whose baked goods include provocatively shaped “sex positive” cookies, saw its sales increase 30 percent during last year’s Pride event, Mr. Jones said. He hopes that the support from local businesses like his, he said, will keep Pride “viable and healthy and vibrant.”