Raised in Petts Wood, Gunning began swimming at the age of four and joined Beckenham Swimming Club at the age of seven. His talent quickly emerged as he broke 15 County records, 9 London Region records, and qualified for his first National Championships at the age of 12 in the 200m Butterfly. In 2010, he made his Team GB debut at the LEN European Open Water Championships. Following the London 2012 Olympic cycle, Gunning reignited his career after relocating north to train at the Stockport Metro High Performance Centre, while also earning a First-Class Honours degree in Early Childhood Education.

In 2017, Michael’s life took a dramatic turn when he was caught in the Manchester Arena bombing. This pivotal moment inspired him to represent Team Jamaica, his father’s birthplace, with the aim of growing the sport in the Caribbean. Although he narrowly missed selection for the 2018 Commonwealth Games, Gunning chose to prioritise life beyond competition and came out publicly as gay on E! Entertainment, becoming the Caribbean’s first openly gay national team athlete. Since then, he has become a leading voice within sport and the LGBTQ+ community, championing authenticity and inclusion.

Since officially retiring from competitive swimming in 2022, Gunning has transitioned into media and advocacy, appearing on programmes including Lorraine, Morning Live and BBC Children in Need. A presenter, pundit and speaker, he hosted live swimming events at the Birmingham 2022 Commonwealth Games and now serves as a Pride House Ambassador for the LA 2028 Olympic and Paralympic Games. Through his work with Speedo and his Swim United campaign, he continues to champion equality, diversity and inclusion, using his platform to inspire change and create opportunities for underrepresented communities.