Informal caregivers of patients with Alzheimer’s disease (AD) often experience high stress and reduced wellbeing and quality of life. HeartMath’s Heart Lock-In® technique has been shown to reduce stress. In a randomized controlled pilot study among ten informal AD caregivers, we examined a two-week ten-minute daily, internet delivered heart-focused breathing protocol (n = 5) compared to waitlist control (n = 5). Participants completed pre- and post- self-assessments of perceived caregiver burden, stress, quality of life, anxiety, self-compassion and heart rate variability (HRV). Quality of life improved significantly in the control group compared to intervention, while self-compassion and HRV trended towards the expected direction. Caregiver burden and anxiety worsened in the intervention vs. waitlist control, suggesting the perception of added stress related to the required new daily task. While heart-focused breathing may hold promise for improving aspects of the caregiving experience, exploring online delivery methods and schedules that do not add extra burden is needed.