Lignocellulosic biomass, such as corn stover, pulp and paper mill waste, and switchgrass, is a readily available feedstock for the production of monomeric sugars and platform chemicals that can then be transformed into valuable organic molecules. However, efficiently fractionating lignocellulosic biomass is difficult due to the recalcitrance of lignin at mild reaction conditions and the reactive sugars/platform chemicals at more severe conditions. Biphasic systems present a possible solution to creating an economically viable biomass upgrading process since sugars prefer the aqueous phase while the lignin and furans partition to the organic phase. This review focuses on recent work to fractionate biomass using biphasic reactions as well as monophasic reactions that use biphasic systems to separate products. The use of different biphasic media, heterogeneous and homogeneous catalysts, and reaction conditions are reviewed and trends in isolating the fractions found in biomass are discussed.