He played the titular role of Bugsy Malone in a stage production at the
Grand Opera House, Belfast in July 2011. He later had a role in a production of
Honk! at the same venue. Braniff relocated to south London at 18 where he attended Italia Conti school of performing arts. He attained his degree in Acting before graduating. Braniff had his first screen role playing rookie cop Tommy Foster in BBC police drama
Blue Lights. For the role, he researched "body language of how police handle themselves in certain scenarios". He has described his attempts to show "the human side" of the police "with their good bits and bad bits”. Speaking of his relationship with Dormer, Braniff said he will "speak to him regularly… [the way our characters were] that maybe spilled over into real life". The series was renewed for a second series, airing April 2024. Ahead of the second series, Braniff described attending a "police boot camp", and during filming on location in Belfast he was met with "positive" reactions from local people who had seen the first series.
Blue Lights was renewed for a third and fourth series in 2024. ==Personal life==