The process-genre approach, varied feedback types, and technology integration have been shown to improve students' writing skills, but there is little research on how these three variables interact when implemented together in writing instruction. This study applied a quasi-experimental design with a sequential explanatory design to integrate the process-genre approach, teacher and peer oral and written feedback, and an online technology platform into a Thai university's English writing course. The experimental group received interventions, whereas the control group received standard writing instruction with papers and teacher and peer feedback. Writing pre- and post-tests, formative writing assignments, teacher, peer, oral, and written feedback surveys, and semi-structured interviews were the evaluation instruments. Descriptive statistics, the Wilcoxon Signed Rank Test, the Mann-Whitney-Wilcoxon test, Spearman's correlation, and Kendall-Theil regression were used to examine quantitative data. A thematic analysis examined qualitative data. The experimental group scored higher on post-tests than pre-tests, indicating that they valued instructor feedback more than other types of feedback. Task response and lexical resource showed substantial gains, although coherence and cohesion, grammatical range, and accuracy did not. The control group had no significant changes in pre- and post-test scores except for task responsiveness. Written feedback was significantly associated with post-test scores and certain post-test criteria in the experimental group. The findings emphasize the importance of a process-genre approach, constant feedback, and technology to improve students' writing.