Multiferroic materials, exhibiting coupled ferroelectric and magnetic orderings, provide a compelling platform for low-power, high-sensitivity magnetic field sensing via the magnetoelectric (ME) effect. This work presents a comprehensive Density Functional Theory (DFT) investigation and device-oriented analysis of representative multiferroics (BiFeO3, TbMnO3, YMnO3). Electronic structure, optical response, and charge transport characteristics are evaluated to establish structure–property–performance relationships. Results indicate that intrinsic ferroelectric polarisation enhances charge separation and reduces recombination, thereby improving signal transduction efficiency. Among the studied systems, BiFeO3 demonstrates superior visible-light absorption, direct band gap, and strong polarisation, making it an excellent candidate for energy-efficient ME sensors. Design guidelines, device architectures, and performance metrics are proposed to bridge materials discovery with practical sensor implementation.