Hundreds of advertisers, including major brands like L’Oreal and Vic toria’s Secret, flocked to the Lower East Side on Thursday night for TikTok’s annual spring pitch to marketers. It had been about a week since President Biden signed a law

that says TikTok must be sold from its Chinese parent company or face a potential ban, and marketers were champing at the bit to hear TikTok’s thoughts.

They didn’t have to wait long. Blake Chandlee, TikTok’s president of global business solutions, kicked off the evening by thanking advertisers for their “tremendous support and trust” and said the company considered the law unconstitutional and would challenge it in court.

“We believe the facts and the law are clearly on our side and that we will ultimately prevail,” Mr. Chandlee told more than 300 attendees, some of whom couldn’t find chairs in the crowd. “I want you to know we are not backing down.”

But for the rest of the roughly 45-minute presentation, which took place in a large gallery with the fuchsia and light blue lights of TikTok’s logo, it was business as usual. And it was a keen reminder that Madison Avenue’s concerns about TikTok, which center on how to cleverly market their products and ensure that consumers are seeing their ads, are vastly different from those of Washington, where officials consider the app a national security risk.

Sofia Hernandez, TikTok’s global head of business marketing, declared that TikTok had gone from “being viral to vital” for businesses. The company’s executives introduced new tools for running ads against trends and events like the Summer Olympics in Paris. A Unilever marketing executive described how the Vaseline brand had thrived by tapping into a TikTok skin care trend known as “slugging.” Many marketers were visibly confused until she explained that the term referred to slathering one’s face with petroleum jelly before bedtime to seal in other serums and moisturizers.

“TikTok is the most interesting story in advertising right now,” said Craig Brommers, chief marketing officer of the retailer American Eagle, who attended the event. “That’s why you had a standing-room-only audience waiting to hear what’s next for the most important video platform for Gen Z.”