Route 126 is a highway located entirely within Barton County in the U.S. state of Missouri. Its eastern terminus is at U.S. Route 160 in Golden City (it shares this terminus with Route 37), the only town on the highway. Its western terminus is at the Kansas state line where it continues as K-126.

Route 126 originally ran between Kansas and U.S. Route 71 (for a total of 17 miles) and was later extended further to the east. The road is two-lane its entire length and is relatively straight with only a couple of curves for its entire length. With the future upgrades to US 71, it will likely have an interchange at the junction with that highway.