To evaluate the feasibility and potential effects of a workplace intervention to reduce and break up sitting. Office workers were randomised in clusters to intervention (=22) or control (n = 22). The intervention included a height-adjustable workstation, education, computer prompt software and line manager support. Outcomes included device-measured workplace sitting and ecological momentary assessed (EMA) workplace productivity. Recruitment, retention and data completion rates were assessed. Recruitment (n = 44), retention (91%) and workplace sitting measurement rates demonstrated study feasibility. At 8 weeks, workplace sitting was 11% lower (95% CI: -20.71, -1.30) in the intervention group compared with control participants. Intervention participants were also more engaged, motivated and productive while sitting (p ≤ 0.016). It was feasible to implement and evaluate this office workplace intervention, with potential benefits on workplace sitting and EMA-measured productivity.