Introduction: The present study aimed to investigate the association between the five-factor personality model (FFM), physical fitness, and physical activity (PA), and the effect of firefighting skills training on physical condition in firefighter recruits. Methods: Data on 58 newly-recruited firefighters from the CELSPAC–FIREexpo human biomonitoring study were used. The sampling protocol was structured in the entry phase testing on the 5th week of training, and final testing on the 10th week of training. During the testing, participants filled out the International Physical Activity Questionnaire (IPAQ) and the Revised NEO Personality Inventory, and underwent analysis of body composition using Dual energy X-Ray Absorptiometry (DXA), a physical work capacity test (PWC 170), a muscular strength test (one repetition maximum bench press (1RM BP) and squat (1RM S)) and the measurement of body weight and height to calculate body mass index (BMI). Associations between study parameters were determined using the Spearman correlation. Results: Extraversion (E) was positively associated with time spent in vigorous physical activity (VPA) and Openness to Experience (O) was negatively associated with time spent sitting. Openness to Experience was also positively associated with BMI and lean mass differences between entry and output measurements. Furthermore, 1 RM S significantly increased during the training program. Conclusion: The observed association between personality from FFM and PA levels in the present study was lower than in the general population reported by other studies. The positive association between E and VPA suggests that using FFM and the relationship between personality and physical fitness as one of the criteria for the selection of suitable recruits may be beneficial.