Childhood obesity represents a significant global health challenge, and treatment interventions are needed. The purpose of this paper is to describe the components and theoretical model that was used in the development and implementation of a unique parent-focussed paediatric overweight/obesity intervention. C.H.A.M.P. Families was a single-centre, prospective intervention offered to parents of children aged between 6⁻14 years with a body mass index (BMI) ≥85th percentile for age and sex. The intervention included: (1) eight group-based (parent-only) education sessions over 13-weeks; (2) eight home-based activities; and (3) two group-based (family) follow-up support sessions. The first section of the manuscript contains a detailed description of each intervention component, as well as an overview of ongoing feasibility analyses. The theoretical portion details the use of evidence-based group dynamics principles and motivational interviewing techniques within the context of a broader social cognitive theory foundation. This paper provides researchers with practical examples of how theoretical constructs and evidence-based strategies can be applied in the development and implementation of parent-focussed paediatric obesity interventions. Given the need for transparent reporting of intervention designs and theoretical foundations, this paper also adds to the areas of implementation science and knowledge translation research.