Abstract Background and Objectives The intersection of cancer, treatment, and aging accelerates functional decline. Social networks, through the provision of social support and resources, may slow the progression of functional deterioration. Socioemotional selectivity theory posits that aging and major life events, like cancer, cause an intentional social network pruning to procure and maintain emotionally fulfilling bonds, while shedding weaker, less supportive relationships. However, it is relatively unknown if such network changes impact functional impairment in cancer survivors. This study examined the relationships between changes in the egocentric social network and functional impairment in older adult cancer survivors and a similarly aged group without cancer (older adults). Research Design and Methods Data were analyzed from 1,481 community dwelling older adults (n = 201 cancer survivors) aged 57–85 years, from Waves 1 and 2 (2005–2006 and 2010–2011) of the National Social Life, Health and Aging Project. Associations were analyzed with multiple logistic regression. Results Cancer survivors and older adults reported similar levels of functional impairment and social network change. Adding 2 new relationships exhibited protective effects against functional impairment, irrespective of cancer status (odds ratio [OR]: 0.64, 95% confidence interval [CI]: 0.41–0.99). Declines in frequent contact were associated with higher odds of functional impairment among cancer survivors (OR: 1.92, 95% CI: 1.15–3.20). Social network components were not significantly associated with functional impairment in older adults. Discussion and Implications Adding new relationships may reduce disability in older adults and increasing network contact may help cancer survivors remain independent. Social network interventions may improve quality of life for older adults.