Redox proteins attached to surfaces designed for biocatalysis hold promise for future clean synthetic routes. It is advantageous for these biocatalysts to operate in low-toxicity fluids with a high capacity to dissolve reactants. Here we report cross-linked films of myoglobin (Mb) and poly(L-lysine) (PLL) chemically attached to oxidized carbon cloth cathodes that in microemulsions feature the protein in a water-rich film environment with reactant in an oil-rich environment. These cross-linked Mb/PLL films were the most stable in microemuslions and had the largest turnover rates for epoxidation of styrene compared to lightly cross-linked or uncross-linked Mb/poly(styrene sulfonate) films. Up to 40-fold larger turnover rates were found in bicontinuous microemulsions compared to oil-in-water microemulsions and micelles. Enhanced turnover rates are correlated with up to 10-fold faster mass transport of solutes in the oil phases of the bicontinuous fluids.