Many older patients with myeloid neoplasms experience treatment-related toxicities. We previously demonstrated that a home-based, progressive aerobic walking and resistance exercise program (EXCAP) improved physical and psychological outcomes in patients with cancer. However, older patients have more difficulty adhering to exercise than younger patients. Reasons may include low motivation, difficulty with transportation, and limited access to exercise professionals. To improve exercise adherence, we integrated a mobile app with EXCAP (GO-EXCAP) and assessed its feasibility and usability in a single-arm pilot study among older patients with myeloid neoplasms undergoing outpatient chemotherapy. GO-EXCAP intervention lasts for 2 cycles of treatment, and the primary feasibility metric was data reporting on the app. Usability was evaluated via the system usability scale (SUS). Patients were interviewed at mid and postintervention to elicit their feedback, and deductive thematic analysis was applied to the transcripts. Twenty-five patients (mean age, 72 years) were recruited. Recruitment and retention rates were 64% and 88%, respectively. Eighty-two percent (18/22) of patients entered some exercise data on the app at least half of the study days, excluding hospitalization (a priori, we considered 70% as feasible). Averaged daily steps were 2848 and 3184 at baseline and after intervention, respectively. Patients also performed resistance exercises 26.2 minutes per day, 2.9 days per week at low intensity (rate of perceived exertion 3.8/10). Usability was above average (SUS, 70.3). In qualitative analyses, 3 themes were identified, including positive experience with the intervention, social interactions, and flexibility. The GO-EXCAP intervention is feasible and usable for older patients with myeloid neoplasms undergoing outpatient chemotherapy. This trial was registered at www.clinicaltrials.gov as #NCT04035499.