The present study aimed to predict marital satisfaction based on relationship beliefs among couples in Shiraz. The family, as the most fundamental social institution, plays a vital role in the psychological and emotional well-being of its members, and marital satisfaction is considered a key indicator of its stability. Since dysfunctional relationship beliefs may lead to recurrent conflicts, misunderstandings, and decreased relational quality, examining their predictive role in marital satisfaction is essential. This study employed a descriptive-correlational design, with the statistical population consisting of all couples who referred to therapeutic centers in Shiraz in 2024. A total of 270 individuals were selected using convenience sampling. Data were collected using the Marital Satisfaction Questionnaire (Ferdosi, 1999) and the Relationship Beliefs Questionnaire (Eidelson & Epstein, 1982). Data analysis with Pearson correlation and simultaneous regression in SPSS-28 revealed a significant negative relationship between dysfunctional relationship beliefs and marital satisfaction. Specifically, the dimensions of “belief in the immutability of the spouse” and “mind-reading expectation” had the strongest negative effects on marital satisfaction. Overall, findings showed that relationship beliefs accounted for about 12% of the variance in marital satisfaction. These results emphasize the necessity of modifying and adjusting relationship beliefs in couples, as such interventions can foster greater compatibility, improve emotional interactions, and enhance marital quality. Therefore, educational and counseling programs focused on revising relationship beliefs may serve as effective strategies for promoting marital satisfaction among couples.