Route 173 is a Connecticut state highway in the southern and western suburbs of Hartford, running from Newington to West Hartford.

Route 173 begins at an intersection with US 5 and Route 15 in Newington and heads north, briefly overlapping Route 174 before continuing into West Hartford. In West Hartford, it continues northeast, then turns west and north along suburban streets. It intersects I-84 shortly before ending at an intersection with Hooker Drive.

A section of Route 173 in West Hartford from the Newington town line to SR 529 is designated the Roger Fissette Hannon-Hatch VFW Post 9929 Memorial Highway. A section from SR 529 to South Main Street in West Hartford is designated the Trooper Carl P. Moller Memorial Highway.

Route 173 was commissioned in 1932. It originally went using South Quaker Lane to Farmington Avenue (then Route 4) in West Hartford. In 1962, Route 173 was truncated to end at Route 71. However, in 1969, it was re-extended slightly to I-84 along South Main Street (former SR 569) via a short overlap with Route 71.

The entire route is in Hartford County.