This review explores the relationship between urban energy planning and smart city evolution, addressing three primary questions: How has research on smart cities and urban energy planning evolved in the past thirty years? What promises and hurdles do smart city initiatives introduce to urban energy planning? And why do some smart city projects surpass energy efficiency and emission reduction targets while others fall short? Based on a bibliometric analysis of 9320 papers published between January 1992 and May 2023, five dimensions were identified by researchers trying to address these three questions: (1) energy use at the building scale, (2) urban design and planning integration, (3) transportation and mobility, (4) grid modernization and smart grids, and (5) policy and regulatory frameworks. A comprehensive review of 193 papers discovered that previous research prioritized technological advancements in the first four dimensions. However, there was a notable gap in adequately addressing the inherent policy and regulatory challenges. This gap often led to smart city endeavors underperforming relative to their intended objectives. Overcoming the gap requires a better understanding of broader issues such as environmental impacts, social justice, resilience, safety and security, and the affordability of such initiatives.