Pattern-recognition-based protein sensing has recently attracted attention as an alternative to conventional specificity-based sensing. Herein, we present a simple one-component array consisting of a charged poly-L-lysine modified with environment-responsive dansyl fluorophores (PLL-Dnc) for the identification of proteases. An array of PLL-Dnc dissolved in three buffer solutions with different pH values is capable of producing fluorescent patterns that are unique to each protease via diverse interactions, allowing the identification of eight proteases by multivariate analysis. Although it is impractical to quantify mixed samples of proteases and their inhibitor proteins by conventional enzyme-activity-based assays, the present array has enabled the discrimination of mixtures of trypsin and α1-antitrypsin (ATT) with different compositions. Considering that the PLL-Dnc array has high accessibility and consists of only a single polymeric material that can be easily prepared, our method is expected to allow screening for the formation of protein-protein complexes, as well as the detection of disease-associated proteases.