The issue of valuation variation in real estate has received increasing attention from researchers in recent years. Valuation variation generally refers to differences in property valuations made by different real estate appraisers, influenced by the appraisers’ individual beliefs. These differences arise from each appraiser’s subjective values and the different strategies they use in their valuation process. From a behavioral finance perspective, this study examines the effects of mental accounting, heuristics (availability and anchoring), and client stress on real estate appraisers’ valuation variation. Because mental accounting, heuristics, and client stress are treated as latent variables, we used structural equation modeling to analyze appraisers’ decision-making in their valuations. The empirical results show that mental accounting has a positive and significant effect on valuation variation, while client stress has a negative and significant effect. Additionally, the availability heuristic, mental accounting, and client stress have a positive and significant effect on anchoring; however, anchoring does not have a significant effect on valuation variation.