He was seen in the teen slasher film Demons Never Die, playing Ricky, and appeared in the BBC Two comedy Episodes, alongside Matt LeBlanc and Stephen Mangan.

In 2012, Anderson was cast for the third season of HBO's television series Game of Thrones as Grey Worm, the leader of Daenerys Targaryen's Unsullied army.

[12][13][14][15][16] In their 2024 best performance reviews, Jackson McHenry of Vulture gave Anderson' performance "immense credits" for grounding the series,[17] while Daniel Canfield of Vanity Fair praised Anderson’s ability to fully embrace "the majestic emotional range required" in his portrayal.

In 2013, Anderson signed to Columbia Records, and released a free three-track EP, The Middle Child, under the stage name Raleigh Ritchie.

Anderson's musical influences include Erykah Badu, David Bowie, Jill Scott, The Smiths, and Stevie Wonder.

[19] In March 2014, his track "Stronger Than Ever" from Black and Blue was remixed by UK garage producer MJ Cole and released as a standalone single.

"Stronger Than Ever" has been used in television adverts promoting the launch of ITV Encore, as well as in montage videos during Sky Sports' coverage of Professional Darts Corporation events.

[20] He also featured on Stormzy's debut album Gang Signs & Prayer track 13 – "Don't Cry For Me" which was released on 24 February 2017.

[30] Described as a 13-track EP, Dead Ends and Diversions features songs that had never made onto an album and several recordings from his live-stream event at The O2 Arena.