He first became known for playing Gary Preston in the BBC One sitcom Miranda (2009–2015) before achieving wider recognition for his role as Lucifer Morningstar in the Fox urban fantasy series Lucifer (2016–2021), a role he reprised in the Arrowverse franchise's "Crisis on Infinite Earths" crossover (2019).

He also appeared as King Cenred on the BBC fantasy series Merlin (2008), Justyn in Channel 4's No Angels, and Thomas Milligan in the Doctor Who episode "Last of the Time Lords".

[8] He reprised the role of Lucifer during The CW's The Flash episode of the Arrowverse crossover "Crisis on Infinite Earths".

[11] They had two daughters together before she filed for divorce in September 2013, citing adultery after he admitted to having an affair with an unnamed co-star while filming Gothica.

[15][16] Ellis married American screenwriter Meaghan Oppenheimer on 2 June 2019,[15][17] and their daughter was born via surrogate in November 2023.