As digital technologies advance, social robots and new media are increasingly recognized for promoting psychosocial well-being in older adults by offering emotional support, cognitive engagement, and social connectivity. This paper introduces a three-dimensional taxonomy—Quality of Life (QoL), New Media Immersivity, and Robot Sociality—to systematically evaluate these technologies’ contributions to eldercare. A review of 234 peer-reviewed studies (2014–2024) highlights a predominant focus on emotional and social well-being, moderate emphasis on cognitive health, and limited exploration of physical health. The taxonomy reveals how integrating social robots and immersive platforms can address loneliness, cognitive decline, and other psychosocial challenges. Additionally, based on the findings, this paper constructs detailed personas to simulate diverse user scenarios using PersonaGPT–underscoring how personalized digital companions can be tailored for varied older adult profiles. By identifying research gaps and offering structured guidance, this work advances the development of personalized digital companions to enhance the quality of life for older adults.