Howell uploaded his first YouTube video titled "HELLO INTERNET" on 16 October 2009. He was encouraged by "some friends" including Phil Lester to continually upload videos to the site. He also has a second channel, danisnotinteresting, which has over 1.7 million subscribers and 52 million views, as of May 2017. He currently broadcasts weekly hour-long live shows on this channel, as well as on YouNow. Together with Phil Lester, Howell presented Dan and Phil on BBC Radio 1 from January 2013 until August 2014, and since September 2014 has been one of the presenters on the station's The Internet Takeover slot.
In August 2014, it was announced that the last Dan and Phil show would be broadcast on 24 August, with the duo moving to a different show on Monday nights, featuring other popular video bloggers. This new show was titled The Internet Takeover, and featured Howell along with Lester live on the first Monday of every month, before coming to an end in April 2016. On 1 May 2017, Howell posted a video on his channel stating that he had changed the name of his YouTube channel from danisnotonfire to Daniel Howell, after stating issues arising from the danisnotonfire name. 
Relation with Little Mix
- Dan, together with his best friend and roommate Phil Lester, hosted several events Little Mix attended, the BBC Radio 1's Big Weekend, the Teen Awards 2013 and the BRIT Awards 2015. He and Lester also interviewed Little Mix numerous of times.