With the continuous increase in China’s age structure, an increasing number of elderly people live alone without family support and are thus more likely to be placed under the care system provided by the community. However, a six-month field study in Community S of Chaoming Street, Hangzhou, reveals four main problems in the current elderly care service system: high turnover rate of front-line service staff, delayed updating and low utilization of elderly profile databases, rigid standardised service models unable to meet individual needs, and unstable neighbour-assisted volunteer mechanisms lacking a systematic incentive system. To address the above deficiencies, this paper puts forward a computer-assisted collaborative social support system based on social support theory. The framework integrates a nine-dimensional hierarchical needs assessment model, a smart elderly care integrated platform, a dynamic “one-person-one-file” archival mechanism, and a multi-agent collaborative linkage mechanism for formal and informal support resources. Resident L in Hangzhou is a typical case of a solitary older person, and this study will use him as an example to show how digital technology can be applied to precise resource allocation, real-time information sharing, and sustainable service delivery for such vulnerable seniors. The above framework is an extended technology-based solution for improving the service model of community-based care for older adults in urban areas in China.