Sefton's mother worked as a doctor, while his father was a civil servant. He qualified as a doctor in 1995. Early in his medical career, he worked in South Africa, which would later help inspire Good Karma.
Early work included all four of the BBC's popular continuing dramas, Doctors, Eastenders, Casualty and its spinoff, Holby City. In 2017, Sefton created the medical drama The Good Karma Hospital for ITV and Tiger Aspect Productions. The series is shot in Unawatuna in southern Sri Lanka, Thiranagama Golden Beach Restaurant and some other places in Galle District. It was recommissioned for a second series. Filming for the second series started in August 2017 and was broadcast from 18 March 2018. Season 3 has been confirmed and will return in 2019.
In 2016, he created Delicious, starring Dawn French, and in 2017 Trust Me, starring Jodie Whittaker. Due to Jodie Whittaker's casting as the Thirteenth Doctor in Doctor Who, the second series was set on the neurological unit of South Lothian Hospital, following Syrian tour veteran Captain James 'Jamie' McKay.
|The Eustace Bros.||
|Born and Bred||
|Monarch of the Glen||
|Secret Diary of A Call Girl||
|Death in Paradise||
|The Good Karma Hospital||
|The Mallorca Files||
- "Meet The Good Karma Hospital writer who gave up surgery for screenwriting". Radio Times.
- "A dose of Karma". Drama Quarterly.
- Louise McCreesh (13 March 2017). "ITV's The Good Karma Hospital is coming back for a second series". Digital Spy. Retrieved 24 December 2017.
- "ITV orders a second series of The Good Karma Hospital" (Press release). ITV. 12 March 2017. Retrieved 24 December 2017.
- Ben Dowell (12 March 2017). "The Good Karma Hospital is coming back for a second series on ITV". Radio Times. Retrieved 24 December 2017.
- http://www.radiotimes.com/news/tv/2018-05-04/the-good-karma-hospital-series-3-itv/ Radiotimes, "The Good Karma Hospital series three confirmed"
- Dowell, Ben (2 December 2016). "Ten TV shows to watch in December". BBC.
- "Dan Sefton's new psychological thriller starring Jodie Whittaker". BBC Media Centre. 26 July 2017.
- "BBC One's Trust Me will return for a second series WITHOUT Jodie Whittaker". Digital Spy. 23 February 2018.