To address the challenges of low reservoir permeability, high crude oil viscosity, and difficulty in energy replenishment during the development of tight reservoir oil reservoirs in a certain area of the Liaohe Basin, a CO2 huff-and-puff energy replenishment technology was experimentally implemented to enhance horizontal well productivity, recovery efficiency, and energy utilization. Numerical simulations were conducted to predict the maximum allowable injection pressure (6 MPa), bottomhole temperature distribution, and phase behavior, with the maximum injection rate determined to prevent reservoir cold damage. A phased corrosion prevention and control strategy was developed to mitigate horizontal wellbore corrosion risks, enabling a transition from reactive maintenance to proactive protection. Corrosion risk assessments were performed based on wellbore structural characteristics, optimizing tubular material selection and anticorrosion measures. Field trials on two wells demonstrated that CO2 huff-and-puff operations resulted in a daily oil production increase exceeding 3 tons per well and a 15–20% reduction in water cut compared to pre-treatment conditions, achieving significant stimulation effects. This technology provides an effective energy replenishment method for low-permeability unconventional reservoirs post-massive fracturing stimulation, enabling safe and efficient large-scale CO2 injection through precise process parameter optimization. The successful application offers a novel technical pathway for efficient tight oil reservoir development, holding significant implications for enhancing oil recovery and achieving carbon emission reduction targets in such reservoirs.