Hydrogel-based biosensors have emerged as promising tools for early cancer detection due to their high sensitivity, specificity, and stability. This review summarizes recent advances in hydrogel-based biosensors for cancer detection, their synthesis, applications, and challenges. Hydrogels, three-dimensional networks of hydrophilic polymers, mimic biological tissues and can be combined with various biosensors to achieve high sensitivity and specificity. They are suitable for detecting cancer biomarkers in real human samples, offering a non-invasive method for early diagnosis. Hydrogels can respond to various stimuli, such as temperature, pH, light, and redox potential, enabling their use in biosensing applications. They can be designed to detect very low levels of cancer biomarkers, providing a sensitive and non-invasive method for early cancer diagnosis. Hydrogel-based biosensors utilize appropriate transducers to convert biorecognition events into measurable signals, enhancing biomolecule stability and functionality compared to traditional methods. Key parameters such as sensitivity, specificity, response time, and detection range are crucial for evaluating biosensor performance. Hydrogels offer advantages such as mimicking the cellular environment, tailored properties, and signal amplification. However, challenges remain in terms of nonspecificity, low conductivity, and the need for further development before widespread clinical use. The integration of hydrogels with functional materials like metal or carbon nanomaterials can enhance their performance. Recent studies have developed various hydrogel-based biosensors, including peptide hydrogels, DNA hydrogels, and conducting polymer hydrogels, for cancer detection. These biosensors have shown high sensitivity and specificity, with low detection limits and broad dynamic ranges. Despite their potential, challenges such as scalability, stability, and immune response need to be addressed. Overall, hydrogel-based biosensors hold great promise for cancer detection due to their advantages in sensitivity, specificity, and adaptability.Hydrogel-based biosensors have emerged as promising tools for early cancer detection due to their high sensitivity, specificity, and stability. This review summarizes recent advances in hydrogel-based biosensors for cancer detection, their synthesis, applications, and challenges. Hydrogels, three-dimensional networks of hydrophilic polymers, mimic biological tissues and can be combined with various biosensors to achieve high sensitivity and specificity. They are suitable for detecting cancer biomarkers in real human samples, offering a non-invasive method for early diagnosis. Hydrogels can respond to various stimuli, such as temperature, pH, light, and redox potential, enabling their use in biosensing applications. They can be designed to detect very low levels of cancer biomarkers, providing a sensitive and non-invasive method for early cancer diagnosis. Hydrogel-based biosensors utilize appropriate transducers to convert biorecognition events into measurable signals, enhancing biomolecule stability and functionality compared to traditional methods. Key parameters such as sensitivity, specificity, response time, and detection range are crucial for evaluating biosensor performance. Hydrogels offer advantages such as mimicking the cellular environment, tailored properties, and signal amplification. However, challenges remain in terms of nonspecificity, low conductivity, and the need for further development before widespread clinical use. The integration of hydrogels with functional materials like metal or carbon nanomaterials can enhance their performance. Recent studies have developed various hydrogel-based biosensors, including peptide hydrogels, DNA hydrogels, and conducting polymer hydrogels, for cancer detection. These biosensors have shown high sensitivity and specificity, with low detection limits and broad dynamic ranges. Despite their potential, challenges such as scalability, stability, and immune response need to be addressed. Overall, hydrogel-based biosensors hold great promise for cancer detection due to their advantages in sensitivity, specificity, and adaptability.