Informal caregivers have an important role in caring for family members at home. Supporting persons with a chronic illness such as heart failure (HF) in managing their self-care is reported to be a challenge and telemonitoring has been suggested to be of support. Aim: to explore informal caregivers experiences with performing non-invasive telemonitoring to support persons with HF at home for 30 days following hospital discharge in Norway and Lithuania. Methods: A qualitative explorative study of informal caregivers performing non-invasive telemonitoring using lung-impedance measurements and short message service (SMS). Data was collected using semi-structured interviews with informal caregivers of persons with HF in NYHA class III-IV in Norway and Lithuania. Results: Nine interviews were conducted with informal caregivers of persons with HF who performed non-invasive telemonitoring at home. A sequential process of three categories emerged from the data: access to support, towards routinizing, and mastering non-invasive telemonitoring. Conclusion: Informal caregivers performed non-invasive telemonitoring for the first time in this study. Their experiences were of a sequential process that included access to support from health care professionals, establishing a routine together, and access to nurses or physicians in HF care as part of mastering. This study highlights involving informal caregivers and persons with HF together in the implementation and future research of telemonitoring in HF care.