The electrification of urban public transport fleets, particularly transit bus systems, represents a strategic pathway for mitigating environmental emissions, modernizing legacy fleets, and elevating service quality in metropolitan areas. However, the systemic success of this technological transition depends not merely on the procurement of electric buses; rather, it demands simultaneous, cross-sectoral coordination among the transit network, power distribution grids, charging infrastructure deployment, fleet operational dynamics, battery life-cycle economics, and urban governance. Utilizing an applied approach centered on Tehran as a case study, this paper analyzes the multifaceted technical requirements and operational challenges of electrifying a mega-city’s bus fleet. The empirical data were derived via Qualitative Content Analysis (QCA) from a specialized expert symposium, capturing the perspectives of professionals across the transportation, electrical engineering, automotive manufacturing, and municipal management sectors. The findings indicate that bus fleet electrification in Tehran must reject a uniform, blanket procurement approach. Instead, deployment should be prioritized based on line-specific geometric and operational characteristics, local grid capacity, route gradients, passenger demand patterns, charging station siting potential, battery degradation costs, and operator capacities. Furthermore, the substantial gap between nominal and real-world driving ranges, the adverse impacts of unmanaged charging on grid peak demand, hidden liabilities in battery replacement cycles, institutional fragmentation, and the absence of an integrated roadmap emerge as critical risk factors. The paper concludes that achieving a sustainable transition requires shifting from an asset-acquisition mindset toward a phased, data-driven, and integrated energy–transport co-governance framework.