[2] In March 2012, he began to develop the photo-sharing mobile app I'd Cap That, which automatically added meme-like captions to images.

[7][8] I'd Cap That was acquired several months later by a startup called Iddiction, and Ko worked there on the app for two years before quitting in 2014.

His manager gave him a job as a senior iOS developer at her employer Fullscreen, where they would be more relaxed about him leaving midday for content creation as a social media company.

At Fullscreen, Ko also met Noel Miller, a web designer from marketing and fellow Viner, by chance after they had previously talked online.

He and Miller became popular on YouTube with their series That's Cringe, hosted on Ko's channel, where the two react to content they consider dumb.

[20] Ko is also part of the cast of Jimmy Tatro's web series The Real Bros of Simi Valley, which airs on Facebook Watch.

[23] Miller dubbed the pair "Tiny Meat Gang" after joking about "the weird idea of an 'unborn child as an fboy [sic]' posing in a sonogram".

[17][12] However, the two began considering music earnestly after they were contacted by producer Diamond Pistols[24] and released their first extended play Bangers & Ass the same year.

[25] After struggling with repeated demonetization, Ko and Miller began the Tiny Meat Gang Podcast in October 2017 to make up for losses.

"[27] The same year, Post Malone was featured in an episode of their podcast[23] and Tiny Meat Gang released their second EP, Locals Only.

[26][28] Ko and Miller also appeared in a live comedy tour across the United States as Tiny Meat Gang.

[20][29] The Washington Post described it as an example of celebrities dismissing genuine criticism as hate;[30] however, Ko gained around 140,000 subscribers directly after the incident and surpassed four million by late 2019.

[25] In October 2020, Ko hosted an eight-episode podcast on iHeartRadio titled The Pleasure is Ours, with guest stars such as Drew Gooden and Emma Chamberlain, in which they discuss truisms and popular sayings.

[14] Adlan Jackson of The New York Times Magazine noted that as Ko and Miller rose in popularity, many of the figures they have mocked appeared in their videos.

"[19] In October 2021, Ko and Miller co-founded Tiny Meat Gang Studios, a comedy podcast network.

[11][37] In the 2020s, Ko started making popular reaction videos to dating web shows, especially those produced by Jubilee Media and The Cut.

Ko has steadily released singles, such as "Not Going Home" and The Button–inspired "Nightmare" and is a resident DJ at Wynn Las Vegas.

[11] Ko met American teacher Kelsey Kreppel at a friend's party in June 2017, and they began dating three months later.

[43] Due to this, his main YouTube channel entered an eight-month hiatus starting June 29, 2024, resuming activity on February 4, 2025.