Introduction: Low back pain (LBP) is the health condition that carries the greatest disability burden worldwide; however, there is only modest support for interventions to prevent LBP. The aim of this trial is to establish the effectiveness and cost-effectiveness of group-based exercise and educational classes compared with a minimal intervention control in preventing recurrence of LBP in people who have recently recovered from an episode of LBP. Methods and analysis: TOPS will be a pragmatic comparative effectiveness randomised clinical trial with a parallel economic evaluation combining three separate cohorts (TOPS Workers, TOPS Primary Care, TOPS Defence) with the same methodology. 1482 participants who have recently recovered from LBP will be randomised to either a comprehensive exercise and education programme or a minimal intervention control. Participants will be followed up for a minimum of 1 year. The primary outcome will be days till recurrence of LBP. Effectiveness will be assessed using survival analysis. Cost-effectiveness will be assessed from the societal perspective. Ethics and dissemination: This trial has been approved by the University of Sydney Human Research Ethics Committee (HREC) (ref: 2015/728) and prospectively registered with the Australian and New Zealand Clinical Trials Registry (ref: 12615000939594). We will also obtain ethics approval from the Australian Defence Force HREC. The results of this study will be submitted for publication in a prominent journal and widely publicised in the general media. Trial registration number: Australian and New Zealand Clinical Trial Registry (ANZCTR) 12615000939594.