I-376 begins at a cloverleaf interchange with I-80 and PA 760 located four miles (6.4 km) east of Ohio within the Glaciated Allegheny Plateau.

From there, it travels in a southerly direction on the Beaver Valley Expressway, a four-lane freeway with a wide grass median.

Now traveling southeast, the route comes to a partial cloverleaf interchange with the Penn-Lincoln Parkway (US 22 and US 30) and Steubenville Pike (PA 60) in Robinson Township.

The two US Routes join I-376 here in a partially-unsigned concurrency (indicated only on reassurance markers), continuing east-southeastward bearing the Penn-Lincoln Parkway name, and soon reach an interchange with I-79.

From that point eastward, along what was known for many years as I-279, I-376 runs east-southeast through Rosslyn Farms and Carnegie before turning northeast and passing through Green Tree.

Entering the city of Pittsburgh, I-376 winds its way northeast to its second interchange with PA 51 at Saw Mill Run Boulevard, which is also part of a spread-out series of ramps linking Banksville Road (US 19) and US 19 Truck.

This junction, located just before the freeway passes under Mount Washington in the Fort Pitt Tunnel, features the infamous wrong-way concurrency of the northbound and southbound directions of US 19 Truck.

There are single-lane westbound exit and eastbound entrance ramps connecting Carson Street to the freeway between the tunnel's portal and the bridge.

An interchange at the Point connects I-376 to I-279 (Parkway North), which leads to the Fort Duquesne Bridge, as well as Liberty Avenue.

I-376 continues east from the Point, still carrying the partially-unsigned US 22 and US 30, following the north shore of the Monongahela River through the south side of the downtown area (the westbound area by Downtown from Grant Street to the Fort Pitt Bridge is locally known as the "Bathtub" because of a tendency of the underpass to flood in heavy rains).

Parkway East exits the city of Pittsburgh near the southeastern corner of Frick Park, and US 30 leaves the freeway shortly thereafter at PA 8 in the suburb of Wilkinsburg.

I-376 and US 22 (now fully signed) continue in a generally easterly direction through Churchill, Wilkins Township, Penn Hills, and finally Monroeville, where I-376 ends at an interchange with the Pennsylvania Turnpike and US 22 Bus.

This is due to the bonds on newer sections of the Turnpike system (such as the James E. Ross Highway, Amos K. Hutchinson Bypass, Mon–Fayette Expressway, and the Southern Beltway) having not been paid for yet (in the case of the latter two, are only partially completed), whereas the mainline Turnpike and the Northeastern Extension had their bonds paid for decades ago.

[9] The first section of what would eventually become I-376 opened June 5, 1953, from PA 885 (Bates Street) near the Hot Metal Bridge east through the Squirrel Hill Tunnel to US 22 Bus (then US 22) at Churchill.

[23] As part of the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users in 2005, Congress had designated an expansion of I-376 past I-79 and along present day US 22/US 30 and PA 60 through Pittsburgh International Airport and north to I-80 near Sharon.

[3] This routing required some major infrastructure work on US 22 west of Downtown Pittsburgh (particularly at the US 22/US 30 cloverleaf interchange in Robinson Township) and safety improvements to PA 60; though both were controlled-access freeways before the extension, they were not up to Interstate Highway standards in all areas.

The improvements to both the US 22/US 30 cloverleaf in Robinson Township and the Lawrence County leg of the route, as well as replacing all of the signs with the I-376 shield, were funded by the American Recovery and Reinvestment Act of 2009.

[24] The designation of I-279 from Downtown west through the Fort Pitt Tunnel to I-79 was officially dropped and replaced by that of I-376 on June 10, 2009.

This makes I-376 one of the first tolled Interstates with such a marker, which was a new addition to the 2009 edition of the Manual on Uniform Traffic Control Devices.

[30] Along with the Delaware River–Turnpike Toll Bridge (which is affected by the ongoing Pennsylvania Turnpike/Interstate 95 Interchange Project), the Beaver Valley Expressway became one of the first sections of the Pennsylvania Turnpike system to implement all-electronic tolling, which began along the Beaver Valley Expressway on April 30, 2017.

[31][32] The Beaver Valley Expressway was selected as a test area so that the PTC could work out any bugs with mailing non-E-ZPass users bills with their unpaid tolls.

The Greenfield Bridge was finally demolished in December 2015, and a replacement was built over the following two years, officially opening on October 14, 2017.

[38] When the Beaver Valley Expressway started opening in 1991, it would receive the "PA Toll 60" designation, because it was operated by the PTC.