While previous research has extensively examined the interrelationships among writing self-efficacy, writing anxiety, and writing performance, it has largely overlooked exploring the mediating roles of metacognitive writing strategies and writing attitude in these relationships. Utilizing Structural Equation Modeling, this study investigates such mediation in the relationship between writing self-efficacy and writing anxiety among 170 Iranian EFL undergraduates, with gender as a moderator. Data was collected through the Questionnaire of English Writing Self-efficacy (QEWSE), Metacognitive Strategies in Writing (MSW) questionnaire, Second Language Writing Anxiety Inventory (SLWAI), and the Writing Attitude Scale (WAS). The results revealed a negative relationship between L2 writing self-efficacy and L2 writing anxiety. Furthermore, while writing anxiety was negatively associated with positive writing attitude, it was positively correlated with negative writing attitude. Metacognitive writing strategies were found to be negatively related to writing anxiety. It was also found that writing attitude and metacognitive writing strategies mediated the aforementioned relationships and that gender moderated the specified relationships. Highlighting the complex, multidimensional nature of L2 writing, the findings suggest that L2 writing can be improved through enhancing learners’ awareness of the close interrelationship between the affective and cognitive dimensions of L2 writing, as well as through the use of instructional activities that foster favorable relations between these dimensions.