This study designed, implemented, and examined the effectiveness of technology-integrated concept-mapping instruction in promoting conceptual understanding and retention of cell-cycle concepts among Grade 10 biology students. Employing a mixed-methods design within a design-based research framework, the study involved 45 Grade 10 students from Bahir Dar Seventh-day Adventist Secondary School. Data were collected through a two-tier conceptual understanding test (pre-test, post-test, and four-week retention test), student-constructed concept maps, classroom observations, and student reflections. Quantitative data were analyzed using descriptive statistics (mean, standard deviation), paired-samples t-tests, and effect size calculations, while the qualitative data were analyzed through thematic analysis. Results revealed that technology-integrated concept mapping instruction significantly enhanced students’ conceptual understanding and reduced misconceptions about the cell cycle. On the two-tier test, scores improved from pre-test (M = 10.40, SD = 3.47) to post-test (M = 25.49, SD = 1.83), t (44) = 27.70, p < .001, g = 0.77. Retention test scores (M = 20.87, SD = 2.58) remained significantly higher than pre-test scores, t (44) = -19.39, p < .001, g = 0.53, indicating durable learning. Concept map scores increased from pre-intervention (M = 4.2, SD = 5.6) to post-intervention (M = 12.9, SD = 4.3), t(44) = 27.89, p < .001, g = 0.54. Concept map scores four weeks after post- intervention (M = 11.1, SD = 4.7) showed a small but significant decline from post-intervention (g = 0.53). Qualitative findings indicated that concept mapping facilitated knowledge organization and cognitive restructuring. Thematic analysis of student reflections revealed that students valued animations for visualizing processes, concept maps for organizing knowledge, and teacher analogies for clarifying difficult concepts. The study concludes that technology-integrated concept mapping is an effective instructional approach for addressing persistent misconceptions and promoting long-term retention of complex biological concepts. The findings have implications for classroom biology instruction, teacher professional development, and technology integration in Ethiopian secondary school science education.