Beyond their widespread application as genome‐editing and regulatory tools, clustered regularly interspaced short palindromic repeats (CRISPR)‐CRISPR‐associated (Cas) systems also play a critical role in nucleic acid detection due to their high sensitivity and specificity. Recently developed Cas family effectors have opened the door to the development of new strategies for detecting different types of nucleic acids for a variety of purposes. Precise and efficient nucleic acid detection using CRISPR‐Cas systems has the potential to advance both basic and applied biological research. In this review, we summarize the CRISPR‐Cas systems used for the recognition and detection of specific nucleic acids for different purposes, including the detection of genomic DNA, nongenomic DNA, RNA, and pathogenic microbe genomes. Current challenges and further applications of CRISPR‐based detection methods will be discussed according to the most recent developments. This review highlights strategies to detect nucleic acids with high sensitivity and selectivity based on different CRISPR‐Cas systems, emphasizing on the detection of genomic DNA, nongenomic DNA, RNA and pathogenic microbe genomes. The outstanding challenges and future scientific directions ripe for the CRISPR‐based nucleic acid detection techniques were finally discussed.