CRISPR‐based biosensing technology has been emerging as a revolutionary diagnostic tool for many disease‐related biomarkers. In particular, RspCas13d, a newly identified RNA‐guided Cas13d ribonuclease derived from Ruminococcus sp., has shown great promise for accurate and sensitive detection of RNA due to its RNA sequence‐specific recognition and robust collateral trans‐cleavage activity. However, its diagnostic utility is limited to detecting nucleic‐acid‐related biomarkers. To address this limitation, herein we present a proof‐of‐concept demonstration of a target‐responsive CRISPR‐Cas13d sensing system for protein biomarkers. This system was rationally designed by integrating a dual‐aptamer‐based transcription amplification strategy with CRISPR‐Cas13d (DATAS‐Cas13d), in which the protein binding initiates in‐vitro RNA transcription followed by the activation of RspCas13d. Using a short fluorescent ssRNA as the signal reporter and cardiac troponin I (cTnI) as the model analyte, the DATAS‐Cas13d system showed a wide linear range, low detection limit, and high specificity for the detection of cTnI in buffer and human serum. Thanks to the facile integration of various bioreceptors into the DATAS‐Cas13d system, the method could be adapted to detecting a broad range of clinically relevant protein biomarkers, and thus broaden the medical applications of Cas13d‐based diagnostics.