There is growing interest in the role of psychological flexibility as a potential resilience factor in workplace settings for protecting employees against the risk of job burnout. This field study contributes to the literature by investigating the utility of delivering brief ACT-informed training to the entire regional workforce of an innovation and manufacturing organization. A total of 504 employees attended the training, 281 of whom completed study measures prior to the training and three months later. Across the 3-month timeframe, participants reported a statistically small and significant increase in work-related psychological flexibility. Increased psychological flexibility was associated with improved stress resilience, reduced exhaustion, and increased personal accomplishment. No change was observed on the depersonalization component of burnout or task performance. Moderation analyses revealed that residual change associations between work-related psychological flexibility and both exhaustion and resilience were stronger among participants with higher baseline exhaustion. By contrast, work-related psychological flexibility trended toward a stronger residual change relationship with personal accomplishment among participants with lower baseline exhaustion. We interpret these findings from the perspective of resource-based theories of workplace functioning, and highlight the potential of cultivating psychological flexibility as part of organization-wide personnel development initiatives.