Emotional labor refers to the process of regulating both feelings and expressions in response to the display rules for promoting organizational goals. Existing literature has provided strong evidence for the impact of emotional labor (i.e., surface acting and deep acting) on service employees’ emotional exhaustion. However, the empirical examination of the mechanisms underlying this association is largely missing from prior research. Drawing on the social interaction model of emotion regulation, this article reported 2 daily diary studies examining the role of customer treatment toward employees in channeling emotional labor's impact on employee emotional well‐being. Specifically, Study 1 measured emotional labor at the between‐person level as habitual emotional regulation strategies used by service employees, and Study 2 measured emotional labor at the within‐person level to capture its fluctuations. Results showed that employees engaging in more surface acting were more likely to receive negative treatment from customers, which in turn increased their negative affect and emotional exhaustion. Further, employees engaging in more deep acting were more likely to receive positive treatment from customers, which in turn increased their positive affect. Implications and limitations of these findings were discussed.