Mustafa was born in Kohat, in Pakistan's North-West Frontier Province. His family moved to the UAE when he was 10, where his father had a car sales business in Sharjah. His father died suddenly when he was 15.
Mustafa made his One Day International debut against Scotland in February 2014. One month later he also made his Twenty20 International debut against the Netherlands. After the 2014 ICC World Twenty20, Mustafa was appointed vice-captain of the UAE. At the 2016 Asia Cup Qualifier, Mustafa scored 77 runs from 50 balls in the first match against Afghanistan, opening the batting with Muhammad Kaleem. This set a new record for the highest score by a UAE player in a Twenty20 International. Mustafa also took three wickets in Afghanistan's innings, which is also record in international taking 3 wickets and 75+ runs in a same match with the UAE going on to win the match by 16 runs. On 4 April 2017, Mustafa scored his maiden One Day International century, scoring 109 against Papua New Guinea. In the same match, he took his maiden five-wicket haul, taking 5/25. In doing so, he became only the third player to score a century and take a five-wicket haul in the same ODI after Viv Richards and Paul Collingwood. In January 2018, he was named as the captain of the United Arab Emirates' squad for the 2018 ICC World Cricket League Division Two tournament. In August 2018, he was named the captain of the United Arab Emirates' squad for the 2018 Asia Cup Qualifier tournament. In December 2018, he was named as the captain of the United Arab Emirates' team for the 2018 ACC Emerging Teams Asia Cup. Later the same month, he was one of three players to be given an eight-week ban from international cricket for breaching the Emirates Cricket Board's Player's Code of Conduct, after using Twitter to criticise the facilities in Karachi during the tournament. In January 2019, the Pakistan Cricket Board had accepted apologies from all the cricketers involved. In March 2019, he returned to the UAE's squad following his suspension for their series against the United States. In September 2019, he was named in the United Arab Emirates' squad for the 2019 ICC T20 World Cup Qualifier tournament in the UAE. Ahead of the tournament, the International Cricket Council named him as the key player in the UAE's squad. He was the leading wicket-taker for the UAE in the tournament, with eleven dismissals in eight matches.
