Geriatric rehabilitation aims at increasing physical and social activity and maintaining the functional reserve of older people. However, the continuity of geriatric rehabilitation in the outpatient setting is limited due to a lack of structured aftercare programs. In order to overcome this, a three-month multimodal home-based intervention program (GeRas) was implemented. The aim of this early qualitative process evaluation was to assess GeRas in terms of perceived reach, effectiveness/efficacy, adoption/uptake, implementation, and maintenance/sustainability (Domains within the RE-AIM Framework) from the perspective of patients who received the intervention and healthcare providers who were involved in the delivery of the intervention. In a qualitative process evaluation, 13 healthcare providers and 10 patients were interviewed throughout the beginning of the implementation period of GeRas to capture early experiences using a semi-structured interview guide. The interview guide and qualitative content analysis was guided by the RE-AIM Framework. The GeRas program was perceived to be largely well implemented and beneficial by healthcare providers and patients. According to healthcare providers, GeRas showed more advantages compared to usual care. Additionally, outcome expectations were mainly met (Domain 1: Effectiveness). However, the implementation of the intervention delivered via the eHealth system was perceived as challenging (Domain 2: Adoption). Nevertheless, the outpatient physical exercise, the outpatient counselling, and the continuous care after discharge improved perceived well-being regardless of the intervention type (Domain 3: Implementation). To facilitate the continued use of GeRas, technical requirements should be created to increase user-friendliness and to motivate patients to continue the training in the long term (Domain 4: Maintenance). Although initial experiences with the implementation and effectiveness of GeRas were positive in general, organisational and technical issues need to be resolved to enhance sustainable and successful implementation of the GeRas program. German Clinical Trials Register (DRKS00029559). Registered 5/10/2022.