Dhar Mann, the creator of a YouTube channel with more than 25 million followers, first heard about the Cannes Lions advertising festival last year from a couple of friends.

“It was incredible — the amount of brands they met, the amount of opportunities that they walked out getting,” Mr. Mann, 41, said. So this year, he and his wife and the chief executive of his 200-person company, Dhar Mann Studios, flew themselves to the south of France for dozens of meetings with marketers and agencies.

The goal, he said, was to land long-term sponsorship deals for his YouTube channel. Marketers, he said, were keen to take the meetings and learn about his videos.

Mr. Mann’s company has primarily made money through ads on YouTube, he said, but wants to expand revenue, particularly as marketers grow increasingly interested in working with creators to reach consumers.

“Folks are realizing that creators have something special with their audience that paid media can’t get you,” Mr. Mann said.