Heparin is a widely accepted blood thinner used in several therapeutic settings. Typically, heparin is administered as an intravenous infusion, and due to its short serum half-life (approx. 60-90 minutes) must be administered frequently, resulting in patient’s discomforts, risk of infection and overdosing. Herein, we develop an injectable material that sustainably releases heparin to allow for less frequent dosing of patients and reduce the incidence of overdose complications.