This article examines the development planning process in the Benishangul-Gumuz Regional State of Ethiopia and identifies factors influencing its effectiveness. A mixed-methods approach was employed, with data collected from 365 civil servants through surveys and 19 key informant interviews. Multistage stratified random sampling ensured representation across the regional, zonal, and woreda levels. The quantitative data were analysed using binary logistic regression, while the qualitative data were analysed thematically. The results revealed weaknesses such as a top-down approach, weak situational analysis, poor monitoring, and exaggerated reporting. The determinants of planning failure, measured as odds ratios, included infrastructure inaccessibility (OR = 4.4), inadequate financial allocation (OR = 6.8), lack of stakeholder participation (OR = 8.8), political instability (OR = 2.6), and weak innovative capacity (OR = 6.3). The study calls for a pragmatic planning approach that emphasises strong local stakeholder involvement to improve regional development planning.