Provided herein are antibodies, or antigen binding portions thereof, that bind to glucocorticoid-inducible TNF receptor (GITR). Also provided are uses of these proteins in therapeutic applications, such as in the treatment of cancer. Further provided are cells that produce the antibodies, polynucleotides encoding the heavy and/or light chain variable region of the antibodies, and vectors comprising the polynucleotides encoding the heavy and/or light chain variable region of the antibodies.