Globally little is known regarding substance use service providers’ perceptions of substitute behaviours and this significant gap could hinder service provision and recovery outcomes. Semi-structured focus group discussions (including 22 service providers across five sites) were conducted in residential treatment facilities in the Western Cape, South Africa. Service providers recognised substances (e.g. cigarettes and caffeine) and behaviours (e.g. gambling, eating, love, sex, shopping, exercise, and gaming) as potential substitutes. Identified substitute motives included managing cravings; self-medication; filling the experiential void of the primary substance, and time-spending. Concurrent behaviours and addictions were believed to be a key mechanism underlying substitution however, service providers did not uniformly screen for co-occurring behavioural addictions. Substitute behaviours were primarily considered a pathway to relapse and service providers emphasised prevention, detection and family education. To suitably intervene, screening for co-occurring behaviours should be an integral part of the assessment of those presenting for substance use treatment.