Route 188 is a state highway in west-central Connecticut, running in an "L" pattern from Seymour to Middlebury.

Route 188 begins at an intersection with Route 34 in Seymour and heads northeast before crossing into Oxford. In Oxford, it heads northwest across the town before entering Southbury. In Southbury, it heads north along the Eight Mile River, briefly overlapping Route 67 before continuing to intersect I-84 and crossing into Middlebury. In Middlebury, it heads northeast, briefly overlapping Route 64 before turning east across the town and ending at an intersection with Route 63.

Route 187 was commissioned in 1935 from former unsigned state roads, running from the current southern terminus in Seymour to Old Waterbury Road (former Route 135) in Middlebury. In approximately 1943, it was extended to its current northern terminus at Route 63 along the eastern half of former Route 135.

The entire route is in New Haven County.