166 Background: Patients newly diagnosed with AML experience substantial psychological distress as they confront a life-threatening diagnosis requiring an urgent 4-6 week hospitalization to initiate chemotherapy. Interventions to address psychological distress in this population are lacking. Methods: We used a five-step app development process to create a psychological intervention app targeting patients’ needs during the initial hospitalization following a new diagnosis of AML. Patients, caregivers, oncologists, psychologists, and nurses served as stakeholders and were involved in 1) developing a conceptual framework for the intervention; 2) creating an intervention manual that incorporates medical information, psychoeducation, and psychosocial skill-building corresponding to the illness trajectory; 3) translating the intervention manual into a storyline with gamification to enhance patient engagement; 4) creating initial wireframes of the app modules; and 5) refining the app through iterative testing. Results: The app consists of five 20-minute modules which the patient will complete weekly over a 5-week period. The modules consist of 1) supportive psychotherapy to address the initial shock of diagnosis; 2) psychoeducation to manage expectations and mobilize social supports; 3) psychosocial skill-building to promote effective coping; 4) self-care to promote positive health behaviors; and 4) a summary module to reinforce learning points from prior modules. Two bonus modules are available for patients who wish to engage in additional cognitive-based restructuring strategies. We utilized gamification strategies to enhance patient engagement including a) creating an app storyline focused on the patient’s journey during hospitalization; 2) creating a guide character doctor that accompanies the patient through their journey; 3) incorporating videos of AML survivors; and 4) developing a point reward system for completing the modules. Conclusions: We developed a novel psychological intervention app for patients with AML using an iterative development process. Future studies should assess the efficacy of the app in improving outcomes for patients with AML.