This mini-review highlights the very recent development of mussel-inspired hydrogels in biomedical and environmental fields. 3,4-Dihydroxyphenyl-L-alanine (DOPA) and its analogues can not only function as cross-linking mediators in constructing the hydrogel network, but also participate in various intermolecular and surface interactions. The developed mussel-inspired hydrogels have important applications in biomedical field as tissue adhesives, drug delivery carriers and coating materials, or in environmental field as pollutant adsorbents, according to the different physicochemical properties that are attributed to different DOPA chemistries.