Previous physical activity guidelines recommended that adults be active on most or all days of the week. Current guidelines recommend accumulating ≥150 min/week of moderate-to-vigorous physical activity (MVPA), with no recommendation for frequency. This study examined the association between the frequency of physical activity throughout the week and the metabolic syndrome (MetS) in physically active adults. This cross-sectional study included 2324 adults aged 18-64 years from the 2007-2011 cycles of the nationally representative Canadian Health Measures Survey. MVPA was measured over 7 days using Actical accelerometers. Physically active participants (≥150 min/week of MVPA) were assigned to frequently active (≥5 days/week with ≥30 min of MVPA) and infrequently active (1-4 days/week with ≥30 min of MVPA) groups. Associations were examined using logistic regression controlling for age, sex, and education. The relative odds of the MetS was 4.43 (95% confidence interval: 2.26-8.69) times higher in physically inactive participants than physically active participants. Within physically active participants, the relative odds of the MetS was 1.73 (0.87-3.41) times higher in the infrequently active group than the frequently active group. However, this was not a significant difference (p = 0.11), and after adjustment for total weekly MVPA, the relative odds of the MetS in the infrequently active group was reduced to 0.85 (0.42-1.72). The frequency of physical activity throughout the week was not independently associated with the MetS among active adults. Conversely, the weekly volume of MVPA was strongly associated with the MetS.