It is 34.88 miles (56.13 km) long and runs east–west, entirely within Grant County.

OR 402 was established in 2002 as part of Oregon's project to assign route numbers to highways that previously were not assigned.

OR 402 begins at an intersection with OR 19 at Kimberly and heads east through Monument and Hamilton to Long Creek, where it ends at an intersection with US 395.

OR 402 was assigned to the Kimberly-Long Creek Highway in 2002.

The entire route is in Grant County.