Martin Nguyen (born 5 March 1989) is an Australian former mixed martial artist, who competed in the featherweight division. A professional from 2012 till 2025. Nguyen is most notable for his stint in ONE Championship, where he was the former ONE Featherweight and ONE Lightweight World Champion, and was the first two-division champion in ONE's history, having held both belts simultaneously.

Nguyen was born on 5 March 1989, in Sydney, to Vietnamese parents. Attending Ashcroft Primary School and Liverpool Boys High School, Martin played representative rugby league but after suffering constant injuries, decided he was better off away from the game. Nguyen then picked up martial arts at the age of 21, initially just to help lose weight and to find a new hobby, but soon realised he had a natural talent for it.

In the promotional debut, Nguyen faced Rocky Batolbatol on 7 November 2014, at ONE FC: Battle of Lions. He won the fight via a rear-naked choke submission in the second round.

Nguyen was scheduled to face Bashir Ahmad on 27 September 2015, at ONE: Odyssey of Champions. However, Nguyen was instead to face Marat Gafurov for the interim ONE Featherweight World Championship. He lost the bout via a rear-naked choke submission in the first round.

Nguyen faced Edward Kelly on 13 November 2015, at ONE: Pride of Lions. He won the fight via a doctor stoppage technical knockout in the first round.

Nguyen faced Li Kai Wen on 15 April 2016, at ONE: Global Rivals. He won the fight via technical knockout in the first round.

Nguyen faced Christian Lee on 13 August 2016, at ONE: Heroes of the World. He won the fight via a guillotine choke technical submission in the first round.

Nguyen faced Kazunori Yokota on 14 January 2017, at ONE: Quest for Power. He won the fight via knockout in the first round.