Issue addressed: Physical activity and exercise participation is limited by a perceived lack of time, poor access to facilities and low motivation. The aim was to assess whether providing an exercise program to be completed at the workplace with or without direct supervision was effective for promoting health-related physical fitness and exercise participation. Methods: Fifty university employees aged (Mean ± SD) 42.5 ± 11.1 years were prescribed a moderate- to vigorous-intensity aerobic and resistance exercise program to be completed at an onsite facility for 8 weeks. Participants were randomly allocated to receive direct exercise supervision or not. Cardiorespiratory fitness (V̇O2max) and maximal muscular strength were assessed at baseline and 8 weeks. Self-report physical activity was assessed at baseline, 8 weeks and 15 months post-intervention. Results: Attendance or exercise session volume were not different between groups. Cardiorespiratory fitness (Mean ± 95% CI); +1.9 ± 0.7 mL·kg·min−1; P < .001), relative knee flexion (+7.4 ± 3.5 Nm·kg−1%; P < .001) and extension (+7.4 ± 4.6 Nm·kg−1%; P < .01) strength increased, irrespective of intervention group. Self-reported vigorous-intensity physical activity increased over the intervention (mean ± 95% CI; +450 ± 222 MET·minutes per week; P < .001), but did not remain elevated at 15 months (+192 ± 276 MET·minutes per week).Conclusion: Providing a workplace exercise facility to complete an individually-prescribed 8-week exercise program is sufficient to improve health-related physical fitness in the short-term independent to the level of supervision provided, but does not influence long-term participation. So what? Lower cost onsite exercise facility supervision is as effective at improving physical health and fitness as directly supervised exercise, however ongoing support may be required for sustained physical activity behaviour change.