This study focused on paragraph writing abilities as it is a fundamental skill for academic and professional success. Improving paragraph writing lays the groundwork for addressing advanced writing tasks and is vital for effective global communication in English. The objective of this study was, therefore, to examine effects of blended instruction on students' paragraph writing performance at Pharma College Hawassa Campus, Ethiopia. A quasi-experimental design was used to attain this objective. A sample of 54 first-year pharmacy department (26 control and 28 experimental) students was taken purposefully. The control group attended conventional, face-to-face approach; whereas experimental group received instruction using blended learning approach via Google Classroom, which incorporated collaborative writing that allowed for peer interaction and scaffolding, extensive online resources for independent learning, face-to-face support, and feedback. Pre-test and post-test paragraph writing were conducted to test effects of blended instruction, and effect size was computed to measure the magnitude of intervention. Furthermore, students' questionnaire was used to collect data on participants' backgrounds and experiences. Results revealed improvements in both groups; however, overall, the experimental group in post-test demonstrated significantly better paragraph writing with a large effect size. Regression analysis highlighted flexibility, collaborative tasks, and instant feedback as key contributors to improvement, whereas impact of authentic materials and face-to-face interactions was comparatively less. Finally, the researchers recommended EFL teachers should benefit from applying blended instruction, which may in turn improve students' paragraph writing performance in English language in the Ethiopian context.