State Highway 21 also known as SH-21 is a state highway connecting Halebeedu of Hassan and Ane Chowkur forest of Mysuru district, in the south Indian state of Karnataka. It has a total length of .
Major towns and villages on SH-21 are: Halebeedu, Rajagere, Kyathanakere, Ramadevarahalla kaval, Kondajji, Salagame, ISRO Master Control Facility-Govindapura, Mavinahalli, Dasara Koppalu, Hassan, Hanumanthapura, Agile, Kattaya, Gorur, Ankanayakana halli, Arkalgudu, Mokali, Baraguru, Dodda Magge, Mugaluru, Ramanathapura, Maradi, Raagimaruru, Mallapura, Halaganahalli, Gorahalli, Bettadapura, Coorgal, Eechuru, Hitnehebbagilu, Periyapatna, Boodithittu and Ane Chowkur (Nagarahole).