On election night, Hasan Piker, 29, was dressed in a navy blue “Bernie 2020” sweatshirt and a “Democracy Now!” baseball hat when he plopped down in a chair to address his digital audience.

“I told you guys like a hundred times that places in the Rust Belt have a lot of mail-in ballots they’re not counting immediately,” he said. “What you’re seeing right now is incomplete data!” The words that followed were peppered with expletives.

Since then, Mr. Piker, a progressive political commentator known for his frenetic onscreen presence, has been the most-watched streamer on Twitch. He spent more than 80 hours this week in front of his camera, with tons of tabs open on his computer, reading out news and providing analysis for his left-leaning millennial and Gen Z followers. Many say they find his candid, slightly chaotic style more relatable than that of buttoned-up cable news anchors.

“People came to me because they wanted to hear a point of view — and maybe not a manicured point of view either, but an honest point of view,” Mr. Piker said.

Twitch, a platform known for broadcasting video game play, has become a lively political space in recent months. This summer, activists and organizers streamed Black Lives Matter marches and sit-ins for racial equality. “Just chatting” streams, where people monologue or host discussions, oftentimes about politics, have also grown in popularity. In June, The New York Times reported that Twitch has “transformed into an unexpected hub of social activism.”

The recent interest in political content has been a boon for Mr. Piker.

Born in New Jersey and raised in Turkey, Mr. Piker graduated from Rutgers University in 2013, with a double major in communications and political science, and took a job working for his uncle, Cenk Uygur, a founder of “The Young Turks,” a progressive online news and commentary program.

He started off doing ad sales and business development for the program, but eventually wanted to make something of his own. In 2016, Mr. Piker pitched the idea for “The Breakdown,” a “Young Turks” video series on Facebook that would deliver political analysis for a left-leaning audience. His sharp criticisms of the commentator Tomi Lahren and President Trump’s immigration ban proved to be a hit. Before long, Mr. Piker had gained fame as Facebook’s resident “woke bae,” a title he said he resents.

But by 2018, Mr. Piker was experiencing diminishing returns on Facebook, and seeing the rise of right-wing news dominance on the platform. He also noticed the algorithm shifting away from video.

He set up a Twitch channel in March of that year and began streaming sporadically. “I wanted a place where I could have people congregate every day,” he said.

His streams were slow growing; the first had just 35 viewers, but over time he began going on other streamers’ shows and collaborating with fellow content creators, which helped expand his audience. Come 2019, he was streaming for hours at a time, nearly every day. There were some bumps in the road. Mr. Piker has been banned temporarily four times for running afoul of the platform’s copyright and content guidelines.

Throughout, Mr. Piker’s goal has been to rewrite the narrative he sees in the news about the left. He felt that progressives had an image problem in part because news organizations were playing into bad-faith portrayals of activists and organizers.

“Everywhere you went on the internet, accelerated by Fox News, the left was seen as hysterical, emotional, blue-haired social justice warriors,” he said. “They turned the concept of fighting for social justice into something negative.”

“‘SJW’ is considered a pejorative,” he added, referring to the abbreviation of the term “social justice warrior.” “That’s crazy to me. The thing is, those people have a righteous cause, they have the right to be emotional and frustrated, but unfortunately, the right has been able to create a very successful narrative.”

In January, Mr. Piker transitioned to streaming full time. Previously, while still employed by “The Young Turks, he had been essentially working double shifts, working during the day and streaming well into the night and early morning.

The Democratic presidential primary was in full swing, and Mr. Piker covered and analyzed the process for millions online. Twitch sent him an “IRL Backpack” streaming kit that allowed him to broadcast on-the-ground, including from organizing events in Nevada and a Bernie Sanders rally in Boston.

When the Black Lives Matter protests took hold this summer, Mr. Piker covered that too. “I showed what the people on the ground were saying rather than the way local news or the mainstream media was covering it to some degree,” he said. “I broadly criticized the local news networks that hyper-focused on looting and all these other tropes they were building about these protests.”

Mr. Piker kept the momentum up on his channel throughout the debates this fall. On Oct. 20, he played the game Among Us with Representatives Alexandria Ocasio-Cortez and Ilhan Omar for an audience of hundreds of thousands. He also began to prepare his viewers for what he said would be an election night like no other.

On Nov. 3, Mr. Piker woke up, hit the gym, then began to stream — and didn’t stop for 16 hours. His marathon election-night stream has been viewed more than 4.5 million times and had more than 225,000 concurrent viewers at its peak.

What viewers find captivating is the way Mr. Piker consumes information in real time. “Last night I watched Piker and his guests play for time as he clicked on the wrong tab in his disorganized browser at least three times,” Gita Jackson, a reporter for Vice, wrote in an article last week. “I saw myself, and the way that I engage with politics and the news, in not just Piker’s political opinions but the way he uses the internet itself.”

Anne Alexander, a 33-year-old New Yorker, watched Mr. Piker’s channel for hours the day after the election. “Hasan consumes the internet at the speed of the internet,” she said. “He has 50,000 tabs open and he’s going from Fox to CNN to Twitter to whatever. He’s consuming news from across the aisle. He’s on social media, on reputable news sources, he’s also reading all the comments that come in, then sometimes he’s listening to commentators and responding to them. It’s extremely dynamic.”

Sara Clemens, Twitch’s chief operating officer, said Mr. Piker’s stream was one example of how Twitch has diversified its content beyond video games over the past year. She said his stream reached Twitch’s “core” viewership: millennials and Gen Z.“It’s a really powerful way to engage with that audience,” Ms. Clemens said.

Though he frequently hosts journalists from mainstream news outlets, Mr. Piker said he doesn’t have a desire to pursue a career in cable news. In fact, he said that being so comfortable streaming for hours gave him an advantage over cable news on election night.

For the pundits and analysts working long hours this past week, he said, 10-and 11-hour days in front of the camera are unusual. But for Mr. Piker, it’s the norm. “I stream those hours every single day,” he said.