This research accordingly examines the effect of childhood social relationships on the use of mobile payment and e-money among Chinese middle-aged and older adults from a life course perspective and tests the mediation role of social activities in such a path with the Karlson–Holm–Breen (KHB) method. The findings support that good childhood community relationships, peer relationships, and close relationships positively affect mobile payment and electronic money use when people enter middle and old age. These effects are significantly mediated by social activities in later life. The findings make marginal contributions to life course theory (LCT), with practical implications for individuals, commercial enterprises, governments, and societies in their efforts to facilitate a society that promotes the digital inclusion of middle-aged and older adults.