The efficacy of explicit measures in assessing fire interest is often compromised by social desirability biases, presenting a challenge for early intervention programs aimed at preventing firesetting behaviour. The current study aimed to validate a novel fire interest Implicit Association Task (IAT), as a more reliable measure of implicit fire interest in adolescents. An Australian community adolescent sample of 85 participants, aged 10–17 (M = 13.65, SD = 1.81), completed a series of questionnaires, and the novel fire interest IAT. Based on self-reports, participants were classified as firelighters (n = 52) or non-firelighters (n = 33). IAT outcomes revealed an inclination towards associating “fire” with “interesting.” Notably, firelighters, compared to non-firelighters, performed significantly quicker during hypothesis-consistent trials of the IAT where fire-images were paired with interesting-words. Moreover, a weak correlation emerged between the speed of responses in these hypothesis-consistent IAT trials and self-reported fire interest. This investigation is one of the few that examined the efficacy of implicit measures of fire interest and is the first to do so using a modified IAT. With continued refinement, the fire interest IAT could be successfully used to assist with early intervention programs aimed at preventing child firesetting behaviour.PsychINFO Code: 3230