The primary aim of this study was to describe the contribution of Gaelic football participation to youth physical activity (PA) levels. Secondary aims were to objectively quantify the overall daily PA levels of participants across sex and age, to determine the PA levels achieved during Gaelic football practice sessions and games, and to compare PA levels on days with organized sporting activity (sports days) and days without organized sporting activity (non-sports days). One hundred and sixty adolescents (87 male, 73 female; mean age 14.5 ± 1.8 yrs.) wore an activPAL accelerometer to determine total sitting/lying time, standing time, light intensity physical activity (LIPA), moderate physical activity (MPA), vigorous physical activity (VPA) and moderate-to-vigorous physical activity (MVPA) during a seven day measurement period, including during Gaelic football participation. Participants achieved an average of 58.5 ± 23.6 minutes of MVPA daily. Males accumulated significantly more MVPA daily than females (Males=70.8±22.1 min; Females = 45.5 ± 16.5 min; p < 0.001; η_p² = 0.401) and time spent in MVPA daily significantly decreased with age (p < 0.001; η_p² = 0.299). Participants accumulated significantly more MVPA during games (36.0 ± 9.2 min/hr (60%)) than practice sessions (29.0 ± 8.3 min/hr (48%); p < 0.001; d = 0.80). On sports days, participants accumulated significantly more time in MVPA (Sports Days = 70.1 ± 36.0 min; Non-Sports Days = 54.2 ± 34.0; p < 0.001; d = 0.45) and were 2.16 times more likely to achieve 60 minutes of MVPA (OR = 2.16; 95% CI = 1.60–2.92) than on non-sports days. The results reveal that Gaelic football provides an opportunity for adolescents to accumulate PA, however, participants currently spent more than 50% of their practice time inactive or in low intensity activities. An opportunity remains to enhance the contribution of Gaelic football to overall daily PA levels, by replacing time spent inactive with time in MVPA.