In this article, we introduce a novel magnetometer suitable for millisecond-range magnetorelaxometry. The magnetometer exhibits high sensitivity to weak magnetic fields, approximately 40 pT / √ Hz. It is compact, operates at room temperature, and possesses a wide dynamic range. We also propose a regularized basis decomposition algorithm for processing multiexponential relaxation data. Our research includes a thorough investigation of the sensor's characteristics and feasibility for magnetorelaxometry, encompassing test tube experiments with magnetic micro-and nanoparticles, among other applications.