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Charge separation and many-body interactions at the interface of the light-absorbing semiconductor and contact layer are of crucial importance to the photophysical properties and optoelectronic device performance. Here, we report the exciton many-body interactions and charge transfer dynamics at the interface of metal halide perovskite nanocrystals and graphene derivatives [graphene oxide (GO) and reduced GO (RGO)] using ultrafast transient absorption (TA) and time-resolved photoluminescence (PL) measurements. At the early timescales, the TA spectra of CsPbBr3/GO and CsPbBr3/RGO show an asymmetric derivative feature originating from the exciton many-body interactions. The band gap renormalization and binding energies of exciton and biexciton of CsPbBr3 nanocrystals are significantly reduced in CsPbBr3/GO(RGO) due to the charge transfer and change in the dielectric environment, respectively. More specifically, the exciton (biexciton) binding energy of CsPbBr3 nanocrystals, originally 38 +/- 2 (34 +/- 1) meV, decreases to 27 +/- 1 (22 +/- 1) meV in CsPbBr3/RGO and 17 +/- 1 (15 +/- 1) meV in CsPbBr3/GO. Furthermore, we observe a reduction in the Auger recombination rate and exciton PL quenching in CsPbBr3/GO and CsPbBr3/RGO, corroborating the charge transfer mechanism. Our systematic studies successfully describe photoexcited charge transfer from CsPbBr3 nanocrystals to GO (RGO) in 7.0 +/- 0.4 (4.2 +/- 0.1) ps, which is one order of magnitude faster than the charge transfer for other acceptor materials such as metal oxide, fullerene, anthraquinone, 1-aminopyrene, and phenothiazine. Our results offer insights and guidance for perovskite-based high-performance optoelectronic devices.