<p>Mode-localized sensors are a class of ultra-sensitive resonant sensors that leverage the mode localization effect of weakly coupled systems for signal detection. In this study, a high sensitivity MEMS current sensor based on mode localization is proposed, utilizing a heat-sensitive structure to enhance sensitivity. The heat-sensitive V-shaped beam generates thermal expansion forces in response to current-induced Joule heating, altering the stiffness of weakly coupled resonators and leading to a change in amplitude ratio. The current sensor based on the mode localization principle achieves the highest current resolution in the field of MEMS current sensors. Compared to previous mode-localized current sensors employing shunt resistors, the proposed design achieves a 10-times improvement in amplitude ratio sensitivity. Through rigorous experiments, the sensor demonstrates a noise floor of <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(2.7\,{\rm{nA}}/\sqrt{{\rm{Hz}}}\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mn>2.7</mn> <mspace width="thinmathspace" /> <mrow> <mrow> <mi mathvariant="normal">n</mi> <mi mathvariant="normal">A</mi> </mrow> </mrow> <mrow> <mo>/</mo> </mrow> <msqrt> <mrow> <mrow> <mi mathvariant="normal">H</mi> <mi mathvariant="normal">z</mi> </mrow> </mrow> </msqrt> </math></EquationSource> </InlineEquation> and a resolution of 5.9 nA, achieving a 30-times enhancement over previous designs. The proposed sensor achieves the highest resolution among reported microelectromechanical system current sensors and outperforms handheld digital multimeters, laying a strong foundation for the development of next-generation miniaturized, high-precision current sensing technologies.</p>