Aim: To explore the co-creation of self-care and the use of eHealth among older adults with chronic illness, their informal carers, and healthcare professionals. Methods: This thesis employed various qualitative methods across four studies. Study I aimed to clarify the concept of “self-care monitoring” from a patient perspective through a concept analysis based on a systematic search of peer-reviewed articles from four databases. Study II aimed to describe patients’ and informal carers’ experiences of self-care management and the use of telemonitoring applications, using semi-structured telephone interviews analyzed by qualitative content analysis. Study III aimed to co-create and test a video feedback tool for self-care at home, using an experience-based co-design approach that facilitated collaboration between pairs of older adults, researchers, and service designers through three iterative steps: workshops, development and refinement, and usability testing. Data were analyzed using thematic analysis, employing both inductive and deductive approaches. Study IV aimed to describe healthcare professionals’ experiences of motivating self-care, utilizing individual narrative interviews analyzed by a phenomenological-hermeneutic approach. Results: Study I clarified the concept of “self-care monitoring”, resulting in the definition: “Self-care monitoring is an activity that means a person has to pay attention and be confident and needs routines for tracking symptoms, signs, and action.” Study II described self-care management with telemonitoring at home, captured by the theme “Developing the capability to perform self-care with technology as both an intruder and an invited guest.” Telemonitoring supported skill acquisition and engagement with healthcare professionals but also introduced uncertainties in symptom interpretation and exclusion. Study III co-created and tested two new self-care exercises within the video feedback tool: “Breathing exercises” and “Picking up from the floor.” Older adults found the exercises and feedback valuable for learning, particularly in highlighting movement variability through performance comparison. Study IV described healthcare professionals’ experiences of motivating self-care, revealing “Co-creating sustainable self-care responsibilities” as the main theme, encompassing empowerment through mutuality, reassigning responsibility, and using oneself as a creative tool. Conclusion: This thesis highlights co-created self-care as a dynamic, empowering process shaped by collaboration, shared responsibility, and active engagement among older adults with chronic illness, informal carers, and healthcare professionals. Engagement in self-care strengthens through interactive approaches like peer support, video feedback, and telemonitoring, enhancing motivation, confidence, and adherence. Future research should focus on long-term engagement strategies and integrating eHealth into primary care to improve co-created self-care.