We present an electrically programmable technique that can rapidly assemble proteins into high-resolution, arbitrarily shaped patterns. Controlled protein adsorption is achieved by switching the nanoscale surface arrangement of a triblock copolymer monolayer on microelectrodes in an engineered microfluidic device via an electric potential. Our technique is the first capable of configuring differential protein densities into patterns by varying the applied control voltage, providing the possibility to tune signals for complex analytes, test conditions, or quantification.