BackgroundRegular physical activity improves physical health and mental well-being and reduces the risk of falling in older adults. The randomized controlled “Prevention by lay-assistedOutdoor-Walking in theElderly atRisk” POWER-study investigates whether volunteer-supported outdoor-walking improves physical function and quality of life in older people living independently or in nursing homes. This sub-study explores the experiences of older participants and volunteers in relation to their physical and psychosocial well-being as well as the challenges faced by both groups. A further aim was to explore volunteers’ experience with people living in nursing homes during the first pandemic lockdown (spring 2020).MethodsThe sub-study was designed as mixed-methods approach consisting of 11 individual semi-structured guide-based interviews (nursing home residents), two focus group interviews (volunteers), and a cross-sectional questionnaire survey (volunteers). The interviews were audiotaped, transcribed verbatim, and analyzed by content analysis as described by Kuckartz. Topics addressed in the interviews were triangulated by means of a questionnaire. The quantitative data were analyzed using descriptive statistics.ResultsParticipants’ evaluation of the intervention was generally positive. Nursing home residents appreciated the social interaction associated with the assisted walking, which motivated them to take part regularly, provided a sense of safety, and caused pleasure on both sides. The impact on physical health status of the nursing home residents of this sub-study varied to a large degree as reported in interviews: in some cases, an improvement in physical performance, a decrease in physical complaints, and an improvement in gait or independence was reported. If not, reference was made to previous or sudden illnesses and the advanced age of the participants. Despite the COVID-19-lockdown and the associated restrictions, about 60% of contacts were still possible and participants planned to continue the assisted walks after the lockdown.ConclusionVolunteers have a positive effect on the quality of life, mobility, and general health of nursing home residents. Even more than the improvement of physical performance, social interaction was seen as helpful. Despite their advanced age, the nursing home residents were curious and open to new contacts. When removing the identified barriers, it might be possible to integrate this program into the long-term everyday life of nursing homes.Trial registrationDRKS-ID: DRKS00015188, date of registration: 31.08.2018.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12877-023-04044-4.