Magnetic flux leakage internal inspection is the most widely used online pipeline inspection method. However, because this technique generally requires the pipeline to be magnetized to saturation to achieve optimal detection results, typically necessitating an excitation system. This leads to large detector dimensions and strong adhesion forces, limiting its application in thick-walled, small-diameter pipelines. The low magnetization intensity defect detection technology based on magnetic eddy current effects overcomes these limitations by enabling defect detection and internal/external wall identification at lower magnetization levels, surpassing traditional methods for thick-walled and small-diameter pipelines. Applicable measurement sensors must effectively detect and differentiate wall defects under low magnetization conditions while maintaining compact size and low power consumption to meet system requirements. This article proposes an LC resonant sensor-based technique for low magnetization MFL defect detection in pipelines. The sensor integrates coils with LC resonators to convert defect information from both internal and external pipeline walls into frequency signals. Theoretical calculations and finite element simulations were conducted to analyze the correlation between defect characteristics and frequency responses. Comparative experiments were performed on 15 mm-thick steel plates containing defects of varying types (depth ratios: 50%wt, 40%wt, 30%wt, 20%wt, and 10% wt). Results demonstrate that the proposed sensor can effectively identify 10% wt defects on both internal and external walls within low magnetization current ranges. Type I and Type II coil sensors achieve optimal detection performance at resonant frequencies of 500 kHz and 1.5 MHz, respectively, for outer and inner wall defects. The proposed LC resonant sensor was validated to achieve defect detection at relatively low magnetization intensity.