Objective: Paediatric dental care under general anaesthesia among preschool children in Western Australia is increasing and costly. This study assessed cost-effectiveness of the atraumatic restorative treatment-based (ART-based) approach against the standard care (SC) approach to managing early childhood caries in a primary care setting based on a 1-year pragmatic randomized controlled trial. Methods: Cost-effectiveness analysis, from the service provider perspective, was conducted. Outcomes include number of referral to specialists and dental treatments. One-way and probabilistic sensitivity analyses were undertaken to test the robustness of the cost-effectiveness estimates. Results: Six children in the ART-based group and 62 children in the SC group (n = 127 each group) were referred for paediatric dental specialist care. Children in the ART-based group received more dental services than those allocated to the SC group (mean = 3.8, SD 2.0 and mean = 1.8, SD 1.8, respectively, Wilcoxon rank-sum test, P < 0.01). Total costs of the ART-based approach and the SC group were $137 860 and $178 217, respectively. Based on probabilistic sensitivity analysis, $654 was saved per referral to specialist avoided and $36 was saved per additional dental treatment. The probability that the ART-based approach is cost-saving was 63%. Specialist dental treatment fees had a big impact on the cost-effectiveness estimates. Conclusion: The ART-based approach appears to be a worthwhile intervention because it resulted in fewer referred cases and enabled more treatments to be provided with cost-savings.