Pluronic F127 (PF127) is a copolymer which forms thermosensitive hydrogels. Hyaluronic acid (HA) was grafted to PF127 to form a new hydrogel matrix (HP) for delivery of cisplatin and carboplatin. The physicochemical properties and drug delivery of the graft were examined in this study. HP system (20% HP copolymer in water) exhibited a similar sol–gel transition temperature (28.3 °C) as PF127 system (20% PF127 copolymer in water) but with a shorter gelling process. A stronger structure was obtained by HP system according to scanning electron microscopic (SEM) images and viscosity kinetics. In vitro release test showed the sustained-release characteristics of hydrogels entrapped with cisplatin and carboplatin. The drug release rate from HP hydrogel was slower than that from PF127 hydrogel. The reduction of drug release by HP system as compared to the control solution was more significant for cisplatin than for carboplatin. Such a thermosensitive hydrogel may be advantageous as an injectable therapeutic formulation for anticancer treatment.