Clustered regularly interspaced short palindromic repeats/CRISPR‐associated nuclease 9 (CRISPR‐Cas9) is an RNA‐guided gene editing tool which offers several advantageous characteristics in comparison with the conventional methods (e.g., zinc finger nucleases and transcription activator‐like effector nucleases) such as cost‐effectiveness, flexibility, and being easy‐to‐use. Despite some limitations such as efficient delivery and safety, CRISPR‐Cas9 is still the most convenient tool for gene editing purposes. Due to the potential capability of the CRISPR‐Cas9 system in genome editing and correction of casual mutations, it can be considered as a possible therapeutic system in the treatment of disorders associated with the genome mutations and in particular cancer treatment. In this review, we will discuss CRISPR‐Cas‐based gene editing along with its classifications and mechanism of action. Furthermore, the therapeutic application of the CRISPR‐Cas9 system in mutational disorders, delivery systems, as well as its advantages and limitations with a special emphasis on cancer treatment will be discussed.