[3] In South Africa, McMullen played at under-19 level for KwaZulu-Natal Inland and Dolphins.
[3] In 2024, he was signed by Sudurpaschim Royals for the Nepal Premier League inaugural season.
[5] McMullen made his One Day International (ODI) debut for Scotland against Namibia in December 2022, as part of the ICC Cricket World Cup League 2.
[6] He scored his maiden ODI century two matches later against Oman, finishing with 136 runs from 121 balls.
[4] In May 2024, he was named in Scotland's squad for the 2024 ICC Men's T20 World Cup tournament.