Introduction: People with psychotic disorders face a significant disparity in life expectancy, primarily due to preventable health conditions. Mental health clinicians play a vital role in addressing these issues, yet barriers such as lack of training, low confidence, and unclear role responsibility impede effective interventions. This study explores the motivation, perceived competence, and communication styles of clinicians addressing physical health for young people with first-episode psychosis, using Self-Determination Theory as a framework. Methods: A mixed-methods design was employed, involving semi-structured interviews with six case managers and five psychiatrists at a specialized early intervention service. Thematic analysis identified key themes, and quantitative ratings assessed attitudes, perceived competence, and communication styles. Results were synthesized into Self-Determination Theory constructs. Results: Quantitative ratings highlighted gaps in training, resources, and prioritization of physical health. Seven themes emerged from clinician interviews: 1) role responsibility, 2) constrained autonomy, 3) autonomous motivation, 4) clinician competence, 5) perceived young person’s competence, 6) domain-dependent communication, and 7) the centrality of relatedness for treatment. Clinicians reported a more directive approach for weight-related issues compared to substance use. Conclusion: Clinicians face significant systemic and individual barriers to addressing physical health in first-episode psychosis. Enhancing autonomy-supportive environments, clarifying role responsibilities, and providing targeted training could improve engagement and outcomes. Integrating physical health within mental health care must be prioritized to reduce disparities.