Despite the negative implications associated with increasing age for physical and cognitive health, emotional well-being appears to remain stable, if not improved, with age. This phenomenon is believed to be explained by age-related increases in motivation to regulate emotions and shifts in emotion regulation strategies to compensate for physical and cognitive declines. Yet, past studies have predominantly relied on self-report measures of dispositional strategy use that are particularly susceptible to retrospective biases, and where behavioral measures have been employed, use of regulation strategies has been limited to only one strategy at a time to modify emotional responses. Additionally, there has been limited prior research examining age differences in how emotion regulation strategies are flexibly adapted to shifts in salient contextual features (e.g., interpersonal context, type/intensity of emotion elicited) in daily life. As people often use multiple strategies to regulate their emotions and the contexts in which these strategies are implemented are ever-changing, evaluating the cumulative effects of simultaneous strategy use and strategy flexibility in daily life is critical for understanding the processes underlying age-related changes in emotional well-being. The current study recruited 130 young adults and 130 older adults for an online study where participants were asked to complete a daily diary measure of emotion regulation, in which they responded to questions about their emotional experience, emotion regulation strategy use, and salient contextual features of “episodes” in their daily life. Participants also completed questionnaires assessing overall emotional well-being including affect balance and emotion dysregulation. In Aim 1, we examined age differences in emotion regulation strategy use, variability, and flexibility (i.e., covariation of strategy use with changes in negative affect intensity) in daily life. Aim 2 investigated how strategy use and flexibility are associated with emotional well-being. Finally, Aim 3 assessed the extent to which age-related differences in emotional well-being are explained by age-group differences in emotion regulation strategy use. Relative to young adults, older adults exhibited more frequent acceptance use, less frequent distraction use, less within-strategy variability, greater between-strategy variability, and less within-strategy flexibility. Across age groups, use of expressive suppression and distraction were associated with poorer emotional well-being whereas higher acceptance flexibility, positive reappraisal flexibility, and situation selection flexibility were associated with better emotional well-being. Age group moderated emotional well-being’s relationships with positive reappraisal use, situation selection use, detached reappraisal flexibility, expressive suppression flexibility, distraction flexibility, and situation selection flexibility. Finally, significant age differences in emotional well-being were partially explained by age differences in distraction use and expressive suppression use, but not by emotion regulation flexibility, suggesting that reduced reliance on maladaptive strategy use may help explain preserved well-being in late adulthood. Despite several limitations of the current study (e.g., reliance on self-report data and examination of only one dimension of flexibility), its findings underscore the importance of examining how emotion regulation strategies are implemented in the context of daily life and suggest that how strategies are used and flexibly implemented across different affective contexts, as well as the adaptive value of these strategies, shifts with age.