Abstract The transition from teacher-centred towards student-centred approaches in language teaching, accompanied by developments in educational technology, may lead second/foreign language (L2) teachers and researchers to pay special attention to reverse teaching or flipped classroom. The related literature asserts that this mode of teaching might have both benefits and challenges which could influence teachers and learners’ participation in a flipped classroom. As an attempt to shed more light on the role of flipped classroom in influencing second language learning outcomes and affective variables in language learning, the present study adopted a sequential explanatory mixed-methods approach to investigate the contribution of flipped writing course to Iranian learners’ writing performance, writing motivation and writing anxiety. In so doing, two intact classes were chosen as the participants (N=43) of this research and they were randomly assigned to a Control Group (N = 18) and an Experimental Group (N = 25). Over a period of 16 sessions, the Control Group underwent the traditional writing instruction, whereas the experimental group was taught the same content in a flipped learning mode. Second Language Writing Motivation Scale (SLWMS), Second Language Writing Anxiety Inventory (SLWAI), a semi-structured interview and two-timed writing tasks were given to gather the required data. The results demonstrated that the flipped method of teaching was substantially effective in improving L2 writing performance of the experimental group (F= 22.20, p = 0.000, partial eta squared = 0.35). Also, the results indicated that the flipped instruction had a statistically significant effect on learners’ writing motivation (F= 51.67, p = 0.000, partial eta squared = 0.56). Moreover, the results represented that the flipped instruction significantly decrease learners’ writing anxiety (F=7. 41,p = 0.000, partial eta squared = 0.156). Moreover, the data from semi-structured interviews
