The clustered regularly interspaced short palindromic repeat (CRISPR)/Cas system has shown great promising applications in the area of nucleic acid biosensing. However, because of the dearth of versatile signal transduction strategies, this system is usually compromised to low versatility, moderate sensitivity, and complex operation for non-nucleic acid targets, limiting its clinical transition. Herein, we describe a direct method to establish the correlation between non-nucleic acid analytes and the CRISPR/Cas12a system using a series of rationally designed, aptamer-flanked activator DNA strands, which enable ultrasensitive detection of biomarkers from different species, greatly broadening the possibility of the CRISPR/Cas system in bioanalysis. Meanwhile, the signal output is highly optional and the sensing principle is akin to the traditional enzyme-linked immunosorbent assay (ELISA), so it can be directly imposed on the currently available ELISA platform, further facilitating its application in medical diagnostics.