This review discusses the bioactive modification of poly(ethylene glycol) (PEG) hydrogels for tissue engineering. PEG hydrogels are promising scaffolds due to their tunable mechanical properties, biocompatibility, and ability to support cell adhesion and tissue formation. However, their bio-inert nature limits their effectiveness in providing an ideal environment for cell growth. To enhance their functionality, researchers have developed strategies to incorporate bioactive molecules from the extracellular matrix (ECM), such as cell adhesion peptides, enzyme-sensitive sequences, and growth factors, into PEG hydrogels. These modifications enable the hydrogels to mimic the natural ECM and support specific cellular responses, such as cell adhesion, proteolytic degradation, and growth factor binding. Various methods, including post-grafting, free radical polymerization, thiol-acrylate photopolymerization, click chemistry, and enzymatic reactions, have been employed to functionalize PEG hydrogels with bioactive molecules. The review highlights the recent advances in material design and fabrication approaches that lead to the development of bioactive PEG hydrogels as tissue engineering scaffolds. These hydrogels have shown potential in promoting cell adhesion, tissue regeneration, and controlled release of bioactive molecules. Challenges remain in achieving precise control over the biofunctional cues and ensuring the long-term stability and biocompatibility of the hydrogels. Overall, bioactive PEG hydrogels represent a promising approach for tissue engineering applications.This review discusses the bioactive modification of poly(ethylene glycol) (PEG) hydrogels for tissue engineering. PEG hydrogels are promising scaffolds due to their tunable mechanical properties, biocompatibility, and ability to support cell adhesion and tissue formation. However, their bio-inert nature limits their effectiveness in providing an ideal environment for cell growth. To enhance their functionality, researchers have developed strategies to incorporate bioactive molecules from the extracellular matrix (ECM), such as cell adhesion peptides, enzyme-sensitive sequences, and growth factors, into PEG hydrogels. These modifications enable the hydrogels to mimic the natural ECM and support specific cellular responses, such as cell adhesion, proteolytic degradation, and growth factor binding. Various methods, including post-grafting, free radical polymerization, thiol-acrylate photopolymerization, click chemistry, and enzymatic reactions, have been employed to functionalize PEG hydrogels with bioactive molecules. The review highlights the recent advances in material design and fabrication approaches that lead to the development of bioactive PEG hydrogels as tissue engineering scaffolds. These hydrogels have shown potential in promoting cell adhesion, tissue regeneration, and controlled release of bioactive molecules. Challenges remain in achieving precise control over the biofunctional cues and ensuring the long-term stability and biocompatibility of the hydrogels. Overall, bioactive PEG hydrogels represent a promising approach for tissue engineering applications.