One of Twitch’s most popular streamers said on Friday that he was joining a rival streaming platform, Kick, in a significant blow to the Amazon-owned site and a sign of its increasingly strained relationship with content creators.

Félix Lengyel, a Canadian known online as xQc, is signing a two-year, roughly $70 million contract, with incentives that could push the total to about $100 million, said his agent, Ryan Morrison.

Mr. Lengyel’s deal — about as large as the two-year contract extension signed by the Los Angeles Lakers’ LeBron James last year — could shake up the economics of the online entertainment world.

“This is more than most professional athletes and megastars,” Mr. Morrison said. “This is one of the highest deals in entertainment, period.”

Mr. Lengyel, 27, chats with fans, hosts reality shows and broadcasts himself playing video games. He has become a star in the livestreaming world, with nearly 12 million followers and the ability to attract tens of thousands of viewers at a given time. By some metrics, he is the most popular Twitch streamer.

“Kick is allowing me to try and do things I haven’t been able to before,” Mr. Lengyel said in a statement. “I’m extremely excited to take this opportunity and maximize it into new creative and fresh ideas over coming years.”

Top livestream personalities can earn millions of dollars and attract communities of loyal viewers by broadcasting their content, but a number of them have left Twitch in recent years, attracted by lucrative deals from other platforms like YouTube. And some streamers have complained that Twitch has become less responsive to its online community and more focused on profitability than keeping streamers happy.

Those concerns came to a head last fall when Twitch said it would take a bigger cut of the revenue that top streamers earn from fans who pay to subscribe to their channels. Twitch altered that policy this week and rolled back a recent change restricting the kinds of advertisements that streamers could show during their broadcasts.

Kick, a streaming platform backed by online gaming and gambling sites in Australia, like Easygo Gaming and Stake.com, an online casino, was launched this year and is emphasizing its streamer-friendly policies. It takes only 5 percent of streamers’ earnings from subscriptions, compared with the 50 percent cut that Twitch takes. As a start-up, Kick is prepared to operate at a loss, said Ed Craven, the company’s chief executive.

Mr. Lengyel will be expected to primarily produce content for Kick, but he will not be locked into an exclusive contract with the site and could pop up on YouTube or TikTok occasionally, Mr. Craven said. Mr. Lengyel still plans to appear on Twitch, though not nearly as often as he did before signing the deal with Kick.

Kick is averaging 110,000 livestreams a day, still dwarfed by Twitch’s seven million monthly streamers and 31 million daily viewers. But it has grown quickly and attracted other stars.

“This is about creating something which is really centered around the creator itself and forming a community that is really built around them and not just solely around a corporate structure,” Mr. Craven said. “We don’t feel like we really have a right to dip into your pockets and take a split of that.”