this study aimed to improve secondary school students’ conceptual understanding in the learning of electricity by addressing misconceptions through guided inquiry-based learning integrated with PhET simulations at Bahir Dar, Ethiopia. A pragmatic paradigm followed with mixed-methods approach guided the study. A one-on-one design-based research design guided iterative cycles of design, implementation, evaluation, and refinement of an inquiry-based intervention supported by PhET simulations. A total of 35 Grade 10 students were participated in the study. Data were collected through administration of standardized Electricity Conceptual Understanding test (ECUT), classroom observations, worksheet analysis, and focus group discussions. Quantitative data were analyzed using descriptive statstics and one sample and paired sample t tests, while qualitative data were analyzed thematically. Baseline results revealed widespread misconceptions about current, voltage distribution, resistance, and circuit behavior, indicating low conceptual understanding. Findings show that integrating guided inquiry-based learning with PhET simulations improved students’ conceptual understanding of electricity and reduces misconceptions significantly. To conclude, guided inquiry with PhET simulations is an effective and an alternative instruction for teaching abstract electricity concepts.