This systematic literature review critically assesses power allocation enhancement in Multiple-Input Multiple-Output Orthogonal Frequency-Division Multiplexing (MIMO-OFDM) systems, vital for improving wireless communication efficiency. By meticulously analyzing recent research, it aims to uncover and rigorously evaluate state-of-the-art methods and algorithms for optimizing power allocation in MIMO-OFDM systems. Through an exhaustive exploration, it provides essential insights, aids informed decision-making, and charts the course for future research in this domain. By addressing key research inquiries, including method comparisons, performance evaluations, challenges, and future directions, the review illuminates the path toward optimized power allocation strategies in MIMO-OFDM systems. This article serves as a comprehensive systematic review, offering valuable guidance to wireless communication researchers and practitioners while shaping the future of power allocation optimization in MIMO-OFDM systems.