On November 24, 2008, he started publishing videos on his main channel Linus Tech Tips (LTT) which has 16 million subscribers and 8.27 billion views as of December 1, 2024.

Sebastian worked for the Canadian online computer store NCIX[32] and was asked to be the host for its technology channel, which was created to help demonstrate products.

[36] In a 2014 interview with technology startup website Tech.co, Sebastian said that his favourite YouTubers were TotalBiscuit, Marques Brownlee, and Austin Evans.

[23][24] In August 2023, a controversy emerged via an investigative video by YouTube creator Gamers Nexus, which described issues specific to both Sebastian as an individual, and of Linus Media Group as a whole.

[39] The report detailed how Sebastian had negatively reviewed a prototype water block made by Billet Labs, despite installing it on hardware for which it was not designed.