Taxi driving, a male-dominated occupation, is associated with an increased risk of cardiovascular disease (CVD). The increased risk is linked to a high prevalence of modifiable CVD risk factors including overweight/obesity, poor nutrition, smoking, excessive alcohol consumption and physical inactivity. Behaviour change interventions may prove advantageous, yet little research has been conducted to reduce CVD risk in this population. The purpose of this study was to co-design an eHealth intervention, ‘ManGuard’, to reduce CVD risk in male taxi drivers. The IDEAS framework was utilised to guide the development of the eHealth intervention, with the Behaviour Change Wheel (BCW) incorporated throughout to ensure the intervention was underpinned by behaviour change theory. Development and refinement of ManGuard was guided by current literature, input from a multidisciplinary team, an online survey, a systematic review and meta-analysis, and focus groups (n = 3) with male taxi drivers. Physical inactivity was identified as the prime behavior to change in order to reduce CVD risk in male taxi drivers. Male taxi drivers indicated a preference for an eHealth intervention to be delivered using smartphone technology, with a simple design, providing concise, straightforward, and relatable content, and with the ability to track and monitor progress.