The Western Slope of Colorado refers the region of the US state of Colorado west of the Rocky Mountains.

The region can be considered to be the part of Colorado outside the mountains which is drained by the Colorado River and its tributaries. Its climate is similar to the Great Basin. Historically it was part of the Utah Territory before its inclusion in the Colorado Territory upon its organization in 1861.

It is generally much less populated than the Front Range and has only a few towns over 5,000 people. The primary economic activity is ranching.

The unofficial "capital" of the Western Slope is considered to be Grand Junction.