Fournier’s gangrene (FG) is a polymicrobial necrotising fasciitis affecting genital, perineal and perianal regions. It poses a critical challenge due to its rapid progression and high mortality rates. The use of hyperbaric oxygen therapy (HBOT) has been explored as an adjunct to standard care (surgical debridement, intensive care support and antibiotic therapy) due to its potential to enhance oxygen delivery, and its reported bactericidal and bacteriostatic effects. The aim of this review is to evaluate the efficacy of additional HBOT in FG to patient outcomes. The analysed studies assess parameters including disease severity, infection resolution, mortality, and duration of hospitalisation in patients treated with HBOT versus those receiving standard therapy alone. Many studies suggest decreased mortality rates and improved patient outcomes in patients receiving adjunct HBOT to standard therapy. Nonetheless, the evidence is inconsistent, with other studies reporting no significant improvement in morbidity and mortality. Factors such as small sample sizes, lack of randomisation, heterogeneity of patient groups/demographics, lack of standardisation for HBOT selection, changes to HBOT machines, and variability of HBOT protocols make it challenging to draw definitive conclusions about its efficacy. HBOT may be a beneficial adjunct to standard therapy in treating select patients with FG. Further research is required to establish a standardised protocol for HBOT in FG (including number of sessions and timing of commencement), long-term outcomes, and patient subsets who would most benefit from its use in consideration of practicality, cost-effectiveness, and accessibility.