State Route 86 (or SR 86) is a state highway in southern Arizona that stretches from its junction with State Route 85 in Why east to its junction with Business Interstate 19 in Tucson. It formerly went east to the New Mexico border near Lordsburg, but this eastern segment has been superseded by Interstate 10. SR 86 is the primary east–west highway through the Tohono O'odham Nation. Note that this route is commonly blocked off by US Department of Homeland Security Border Patrol Agents to perform random searches of vehicles, due to its proximity to the Mexico border.

The western terminus of SR 86 is located at a junction with SR 85 in Why. From this intersection, the highway heads southeast, but curves towards the east as it enters the Papago Indian Reservation. It continues towards the east passing through the communities of Schuchuli, Gunsight, Wahak Hotrontk, Plato Vaya, Covered Wells before curving towards the southeast near Quijotoa. It continues southeast until curves towards the east in Sells. It curves towards the northeast near Little Tucson and curves back to the east near San Pedro. The highway curves towards the northeast just prior to leaving the reservation. SR 86 curves towards the east as it enters Tucson. In Tucson, the highway continues east to an interchange with I-19 and continues past the Interstate to its eastern terminus at an intersection with 16th Avenue.

The entire route is in Pima County.