We demonstrate that a common laboratory filter paper uniformly adsorbed with biofunctionalized plasmonic nanostructures can serve as a highly sensitive transduction platform for rapid detection of trace bioanalytes in physiological fluids. In particular, we demonstrate that bioplasmonic paper enables rapid urinalysis for the detection of kidney cancer biomarkers in artificial urine down to a concentration of 10 ng/mL. Compared to conventional rigid substrates, bioplasmonic paper offers numerous advantages such as high specific surface area (resulting in large dynamic range), excellent wicking properties (naturally microfluidic), mechanical flexibility, compatibility with conventional printing approaches (enabling multiplexed detection and multimarker biochips), and significant cost reduction.