Managing workplace anger is essential for maintaining employee well-being and organizational productivity. This study explores the potential of AI-mediated emotion regulation interventions, focusing on the integration of emotion validation into cognitive reappraisal strategies. We examined three hypotheses: (1) whether participants perceive AI-delivered cognitive reappraisal interventions as less effective than those delivered by humans, (2) whether incorporating emotion validation improves perceived success in AI-mediated interventions, and (3) whether emotion validation enhances behavioral emotion regulation outcomes in AI conditions. Results supported all hypotheses, revealing that while AI interventions were perceived as less effective compared to human interventions, the inclusion of emotion validation significantly improved both perceived and behavioral outcomes in AI-mediated contexts. Exploratory analyses identified significant mediators, including perceived support, empathy, attachment, and expertise, which influenced the effectiveness of emotion validation.