This paper reports on the thermogelling, biodegradable polymer formulations based on poly(DL-lactic acid-co-glycolic acid)/(poly(ethylene glycol) graft copolymers for in vivo biomedical applications using animal models. The description includes diabetic control by sustained insulin delivery and cartilage repair by chondrocyte cell delivery. With one injection of the poly(DL-lactic acid-co-glycolic acid)/(poly(ethylene glycol) graft copolymers insulin formulation, the blood glucose level could be controlled from 5 to 16 days in diabetic rats by varying the polymer composition. The cartilage defect was notably repaired using chondrocyte suspension in the thermogelling PLGA-g-PEG compared with a control. This report shows that thermogelling biodegradable PLGA/PEG graft copolymer system can be a promising platform for protein and cell-based therapy.