To explore workers' sitting-reduction and activity-promoting strategy use following an intervention targeting these changes, and whether strategy use and perceived workplace support impacted on 3-month sitting and activity outcomes.This secondary analysis in desk-based workers (n = 83) utilized data collected on questionnaire-derived strategy use and workplace support, and activPAL3-derived sitting (total; prolonged, ≥30 minutes) and activity (standing; stepping) at work.Fourteen strategies were commonly used during the intervention. Increased usage of some strategies were significantly (P < 0.05) associated with beneficial changes in prolonged sitting or stepping only. Workplace support was significantly beneficially associated with changes in sitting, prolonged sitting, and stepping; these associations were largely independent of strategy use changes.Strategies were highly used, with increased use associated with some behavioral improvements. Workplace support appears essential for improving sitting and activity in the workplace.