Electrochemiluminescence (electrogenerated chemiluminescence, ECL), which involves light emission from excited states of electrochemically generated species at the electrode surface, is widely applied for chemical analysis. Integrating the advantages of outstanding selectivity from biological recognition and the high sensitivity of ECL signaling, ECL biosensors are powerful for ultrasensitive bio‐checkups and quantification, in which luminol is adopted as an important luminophore. Nanomaterials have been introduced into ECL biosensors, which enlarge the applicable pH range and improve analytical performances, with successful applications in clinical events. In particular, this Minireview will focus on new progresses related to luminol‐based biosensors and their applications in clinical diagnosis, with emphasis on nanomaterials being employed as the improver.