To assess the relationship between physical activity (PA) in work, transport, domestic, and leisure-time domains (with sitting time included) and health-related quality of life (HRQoL) among young adult men. The long version of IPAQ and SF-36 Health Survey were used to assess PA and HRQoL, respectively, in 1425 voluntary 20- to 40-year-old Finnish male participants. Participants were divided into tertiles (MET-h/week): Lowest tertile (100 MET-h/week). The IPAQ domain leisure-time PA predicted positively the Physical Component Summary (PCS) (ß = 0.11, 95% CI: 0.06 to 0.16) and Mental Component Summary (MCS) (ß = 0.11, 95% CI: 0.05 to 0.16) dimensions. Occupational PA predicted negative relationships in the PCS (ß = -0.13, 95% CI: -0.19 to -0.07), and sitting time predicted negative relationships in the MCS dimension (ß = -0.13, 95% CI: -0.18 to -0.07). In addition, a linear relationship was found between total PA level (including sitting time) and all of the IPAQ domains (