Objectives. There is no consensus regarding the efficacy of self-contained breathing apparatus (SCBA) on firefighters' physiological and psychological stress responses. This study synthesized and quantified the psycho-physiological demands placed on firefighters wearing SCBA compared to a control group. Methods. Five databases were searched with English-language restrictions from inception to January 2021. As dependent variables, physiological (rectal temperature [T-re], mean skin temperature [T-sk], heart rate [HR], maximal heart rate [H-Rmax], maximum oxygen uptake [V-O2max], total sweat rate [TSR]) and psychological (rating of perceived exertion [RPE] and thermal sensation [TS]) responses were continuously collected. This study is registered with PROSPERO (CRD42021228363). Results. Nine eligible studies with 289 participants met the inclusion criteria. The pooled estimates for V-O2max statistically significantly decreased, whereas T-sk, HR, HRmax, TSR and RPE increased significantly. Additionally, the T-re and TS parameters were elevated but not significant. Subgroup analysis revealed that, except for V-O2max and TSR, the SCBA weight did not differ significantly between groups on any outcome measure. Conclusions. Our meta-analysis indicates that wearing SCBA elicits thermoregulatory, metabolic and psychological stress. However, this is not primarily explained by the weight of SCBA, highlighting the value of ergonomic design and physiological monitoring.