We report a Ni2+ heavy metal sensor based on a graphene oxide (GO) functionalized micro-tapered long-period fiber grating (MTLPG) where light-matter interaction is enhanced. With high-quality GO coating on fiber with strong adhesion and controllable thickness, the GO-coated MTLPG demonstrated a resonant wavelength shift and intensity change, corresponding to a sensitivity of up to 5.12 x 10(-4) nm ppb(-1) and 3.07 x 10(-4) dB ppb(-1), respectively. Moreover, the limits of detection were 2.5 ppb and 0.27 ppb, respectively, operating in a wider concentration range of 1 ppb to 1 x 10(7) ppb. The proposed optical platform can be developed for superior chemical sensing applications.