<p>The internet has become ubiquitous in daily life, and its relationship with well-being is a crucial contemporary issue. On the basis of a lifespan perspective and socioemotional selectivity theory, the present study aimed to understand how older adults can benefit from internet usage. Studies 1a (<i>N</i> = 1725) and 1b (<i>N</i> = 1715) leveraged two large, independent, cross-sectional, and nationally representative datasets from the Taiwan Social Change Survey. We found a consistent moderating effect of age: increased internet usage time was negatively correlated with well-being among younger adults, whereas it was positively correlated with well-being among older adults. These findings remained robust even after controlling for socioeconomic status and were observed both before and during the COVID-19 pandemic. In Study 2, we examined the underlying motivational mechanisms (i.e., socioemotional and instrumental goals) of the relationship between internet usage time and well-being using a new sample consisting solely of older adults (<i>N</i> = 795; mean age = 69.58 years). The results indicated that older adults had a stronger preference for socioemotional goals than for instrumental goals of internet usage. Analysis of indirect associations showed that both types of motivation statistically accounted for the relationship between internet use time and well-being, with the associative strength of socioemotional goals being significantly stronger than that of instrumental goals. Overall, our studies (total <i>N</i> &gt; 4,000 participants) highlight the potential for internet usage to serve as a valuable tool in promoting social integration and well-being among aging populations. The implications of these findings, along with their limitations, are discussed.</p>