Fitzgibbon's first race was in 2008 at age 12. As a junior competitor, he joined the Brighton Phoenix running club.[2] In 2014, aged 18 he won the English Schools title in the 1500m representing Sussex.[3]
In 2015, he placed fifth in the 1500m final at the European Athletics Junior Championships in Sweden.[4]
In 2017, he set a personal best over the metric mile of 3:36.97 at the Nijmegen Global Athletics competition. That year, he placed 13th in the 1500m at the London Anniversary Games[5] and set the male record for the Hove Promenade Parkrun at 14:31.[6] At the 2017 European Athletics U23 Championships in Poland, Fitzgibbon placed eighth in the 1500 metres.
In 2018, he set a season's best in the 1500m at the Internationales Soundtrack-Meeting in Tübingen, Germany with a time of 3.39.37.[7]
In 2019, Fitzgibbon represented Great Britain and Northern Ireland at the Glasgow European Indoor Athletics competition, making the final and placing 8th overall.[8][9] It would be his last international level competition.
After Glasgow, he experienced a severe injury to his ankle that would prevent him from elite competition and would impact his mental health.[8][3] After recovery, began distance and cross county running.[2][10]
In 2022, Fitzgibbon was diagnosed with psychosis.[8] He actively spoke out about his mental health,[1] describing coping with his diagnosis as "difficult".[11]
In June 2024, Fitzgibbon won the Bexhill 5km with a time of 15:13. That year, he began training for the 2025 Brighton Marathon, which he planned to run in support of the charity Mind.[4]
Fitzgibbon died on 7 October 2024, at the age of 28.[2]
