This is a reprint of articles from the Special Issue published online in the open access journal Gels (ISSN 2310-2861). This reprint focuses on the modification of hydrogels and their applications in biomedical engineering, aiming to provide a reference for scholars in related fields. It mainly involves the applications of hydrogels in biomedical fields such as phantoms, wound healing, skin, cartilage, muscle, and drug loading. We believe this reprint can provide a valuable reference for scientific and technological workers in the fields of materials science, tissue engineering, biological manufacturing, biomedical engineering, and so on.