Amid the rapid development of e-commerce, merchants increasingly employ cashback strategies for positive reviews to manipulate online feedback and artificially boost sales and reputation. However, such practices systematically distort authentic consumer responses and disrupt fair market competition. According to the Stimulus-Organism-Response(S-O-R) theory, this study provides the first theoretical model to examine how negative emotions induced by cashback for positive reviews influence consumers’ evaluation behavior. An empirical analysis based on 460 valid questionnaire responses was performed using SPSS and AMOS, yielding the following findings. (1) Negative emotions, including disappointment, anger, and regret, significantly triggered psychological contract breach, both transactional and relational. (2) Psychological contract breach reduced consumers’ willingness to provide positive reviews and lowered their store evaluation behavior, fully mediating the relationship between negative emotions and evaluation behavior. (3) Cognitive dissonance partially moderated the pathway from negative emotions through psychological contract breach to review behavior. This study elucidated the influence mechanism of negative emotions in “cashback for positive review” scenarios on consumers’ evaluation behavior, established a “merchant-user” online review relationship model, and provided practical and managerial implications for fostering mutually beneficial outcomes among platforms, merchants, and consumers.

“Cashback for positive reviews” is a common form of e-commerce manipulation that may undermine consumer trust and distort the market evaluation system. However, there is a lack of systematic research on how it influences consumers’ willingness to provide evaluations through psychological mechanisms. This study, based on the Stimulus–Organism–Response (S-O-R) framework, integrates the theories of psychological contract and cognitive dissonance. An empirical analysis based on 460 valid questionnaire responses was performed using SPSS and AMOS, yielding the following findings. (1) Negative emotions, including disappointment, anger, and regret, significantly triggered psychological contract breach, both transactional and relational. (2) Psychological contract breach reduced consumers’ willingness to provide positive reviews and lowered their store evaluation behavior, fully mediating the relationship between negative emotions and evaluation behavior. (3) Cognitive dissonance partially moderated the pathway from negative emotions through psychological contract breach to review behavior. This study elucidated the influence mechanism of negative emotions in “cashback for positive review” scenarios on consumers’ evaluation behavior, established a “merchant-user” online review relationship model, and provided practical and managerial implications for fostering mutually beneficial outcomes among platforms, merchants, and consumers.