The transition from internal combustion engine (ICE) vehicles to electric vehicles (EVs) is a critical step toward reducing greenhouse gas emissions and promoting sustainable transportation. While purchasing new EVs remains a primary solution, converting existing ICE vehicles into EVs presents a cost-effective and environmentally beneficial alternative. This paper provides a comprehensive review of the EV conversion process, including the key technical components such as electric motors, battery packs, and power management systems. It explores the different types of conversions, ranging from full powertrain replacements to partial modifications, and examines the associated challenges, including battery range limitations, vehicle compatibility, and economic feasibility. Furthermore, the study evaluates recent advancements in conversion technologies, such as improvements in battery energy density, fast-charging infrastructure, and the integration of renewable energy sources. By analyzing the latest research findings, the paper compares the performance, efficiency, and emissions reductions of converted EVs with factory-manufactured electric models. Additionally, it identifies critical research gaps, including the need for standardized conversion regulations, comprehensive lifecycle assessments, and strategies to enhance consumer adoption. The findings suggest that EV conversions have significant potential to accelerate the electrification of transportation, particularly in regions where new EV adoption is limited due to economic constraints. However, achieving large-scale implementation requires further advancements in technology, cost reduction strategies, and supportive government policies. This review concludes with recommendations for improving conversion efficiency, reducing financial barriers, and fostering a regulatory framework that facilitates the widespread adoption of EV conversion as a viable sustainability solution.