In this study, injectable hydrogels were prepared by horseradish peroxidase-mediated co-crosslinking of dextran–tyramine (Dex–TA) and heparin–tyramine (Hep–TA) conjugates and used as scaffolds for cartilage tissue engineering. The swelling and mechanical properties of these hydrogels can be easily controlled by the Dex–TA/Hep–TA weight ratio. When chondrocytes were incorporated in these gels, cell viability and proliferation were highest for gels with a 50/50 weight ratio of Dex–TA/Hep–TA. Moreover, these hydrogels induced an enhanced production of chondroitin sulfate and a more abundant presence of collagen as compared to Dex–TA hydrogels. The results indicate that injectable Dex–TA/Hep–TA hydrogels are promising scaffolds for cartilage regeneration.