This 8-week single-arm pilot trial within Kaiser Permanente Northern California tested the feasibility of conducting a mobile app/online-based mindfulness intervention for cancer patients undergoing chemotherapy and their caregivers. Participants were cancer patients with ≥8 weeks of remaining chemotherapy and their informal caregivers, where neither had a regular meditation practice. Participants were given access to a commercially available mindfulness program, Headspace™, via smartphone or computer and were asked to practice meditation using the program for 10–20 min daily. Data were collected on depression, anxiety, sleep, fatigue, quality of life at baseline and post-intervention using validated instruments. Qualitative telephone interviews gathered data regarding participants’ experience with the intervention. Nineteen patients (68%) and 9 caregivers (60%) completed the study. Approximately 40% of the patients had stage 3 or 4 cancer, and 30% were males and non-whites. Among them, 20 (71%) practiced meditation using the app > 50% of the days during the 8-week study period, and 60% of those individuals practiced > 70% of the days. Preliminary before-after comparison data suggested reduction in levels of distress and improvement in quality of life. In qualitative interviews, participants reported ease in use of the mindfulness program and appreciation for the convenience of accessing the program any time. Our results suggest that an app/online-based mindfulness intervention is feasible and well-accepted by cancer patients and their caregivers within an integrated healthcare system.