The accelerating need for decarbonization, driven by global climate targets, has intensified interest in leveraging existing subsurface assets to support the energy transition. At the same time, a significant number of oil and gas reservoirs are approaching the end of their productive life, raising important questions regarding their decommissioning or potential reuse. Repurposing these reservoirs presents an opportunity to transform legacy petroleum infrastructure into valuable components of low-carbon energy systems. This review synthesizes current knowledge on the reuse of depleted petroleum reservoirs for three key applications: geological storage of carbon dioxide, subsurface hydrogen storage, and geothermal energy production. It critically examines reservoir suitability based on geological and petrophysical characteristics, as well as the technical feasibility of each application. Particular attention is given to storage mechanisms, operational constraints, and the role of existing infrastructure in reducing development costs and timelines. The review also addresses cross-cutting challenges, including reservoir integrity, leakage risks, geochemical interactions, and uncertainties associated with long-term performance. While carbon dioxide storage is relatively mature, hydrogen storage and geothermal applications require further validation at scale. Key research gaps are identified in areas such as coupled process modeling, monitoring technologies, and reservoir-specific performance assessment. Overall, repurposing petroleum reservoirs offers a pragmatic pathway to support net-zero objectives by integrating carbon management, energy storage, and renewable energy production within existing subsurface systems.