The effect of multiangle combined magnetic-field annealing (MCMFA) on the GMI performance of melt-extracted Co-based amorphous microwires for sensor applications is studied using a precision impedance analyzer. Experimental results indicated that MCMFA treatment can effectively improve the GMI effect comparing with as-cast and conventional vacuum-annealed (CVA) wires. The maximum GMI ratio [ΔZ/Zmax]max and field response sensitivity ξmax of transverse combined magnetic-field annealed (TCMFA, α = 90°) wires can be increased at 10 MHz to 310.7 and 30.91%/Oe, respectively, through with circumferential anisotropy field expanded and GMI changed from single peak (SP) to double peaks (DPs). DPs behavior of TCMFA wire is due to the typically “nail-sticked” action of magnetic moment rotation at relatively high frequency (up to ≥1 MHz). It can therefore be concluded that MCMFA could be used to develop Co-based microwires with enhanced GMI effect for high-resolution sensor applications.