The study examines the effects of process-genre approach on English majoring university students’ argumentative writing performance in terms of its overall text-quality, rhetorical structures, and linguistic features. To achieve this purpose, a quasi-experimental design particularly time-series-design was employed among regular second year English majoring students at Debre Tabor University in 2019 G.C academic year. Tests and self-reflection reports were used as data gathering instruments. Pre-tests and post-tests were employed to examine students’ argumentative writing performance differences before and after the intervention. The self-reflection reports were used to notice the experimenter’s and students’ responses regarding the impacts of the process-genre approach and its overall applications in the argumentative writing class. The quantitative data were analyzed using descriptive and inferential statistics. The descriptive statistics discussed means and standard deviations of the results of the tests. Frequencies were also employed to analyze the stage-move structures and linguistic features of students’ argumentative texts. On the other hand, the inferential statistics particularly Repeated Measures Analysis of Variance (ANOVA) was computed to examine the significant differences among the tests. Genre analysis and textual analysis were also employed to analyze the generic structures and linguistic features of the students’ argumentative texts. Moreover, thematic analysis was used to analyze the participants’ reflections regarding the impacts the process-genre had on the learners’ argumentative writing performance. The results generally revealed that applying process-genre approach in writing classes had positive effects on students’ argumentative writing performance in terms of writing qualities such as communicative quality, organization, argumentation, and linguistic appropriacy (p <.05). However, the instruction was not found to enhance the students’ written arguments in terms of the linguistic accuracy aspect (p >.05). An attempt was made, furthermore, to see if students’ understanding on the structures and the linguistic features of their written arguments was enhanced as a result of the intervention. It was proved, in the post-test texts, that students showed understanding of the structures and language elements appropriate to the convention of argumentative essay. They were found to use more moves and linguistic elements in the texts carried out in the post-intervention phase than in the texts composed before the treatment. The result also indicates that the participants had positive responses concerning the impacts of the process-genre approach on the students’ argumentative writing performance. The study suggests that since learning writing is a complex task especially at the higher education context, it is essential to teachers to use a process-genre approach whereby both the cognitive and social aspects of writing are addressed; this, in turn, helps learners to overcome the challenges they encounter while composing a particular genre and to gain a complete view of writing. In addition, further investigations should be done that will enlighten the contribution of the process-genre approach to the improvement of students' writing in other discourses.