East of Jamestown, the route straddles the Southern Tier Expressway and connects to the highway in four different locations, including at its eastern terminus.

The route heads to the southeast, paralleling Chautauqua Creek and meeting the New York State Thruway (I-90) at exit 60 a quarter-mile (0.4 km) from NY 5.

NY 394 crosses over the Thruway and enters the village of Westfield, passing baseball fields and local businesses ahead of an intersection with U.S. Route 20 (US 20).

After the intersection with East Campbell Avenue, NY 394 leaves Westfield and heads into rural regions of Chautauqua County.

Roughly 2 miles (3.2 km) from the creek, NY 394 enters the Mayville village limits upon intersecting Beaujean Road.

[4] South of the expressway, NY 394 remains the primary lakeside roadway as it passes through the communities of Quigley Park and Cheney's Point.

NY 394 turns back to the southeast at an intersection with CR 43, passing Edward F. Loomis Park and remaining on the now-southern edge of Chautauqua Lake.

As the route approaches Lakewood, traffic generally becomes more dense and it intersects NY 474, a largely rural roadway linking the Jamestown area to Wattsburg, Pennsylvania.

[4] NY 394, initially known as Sixth Street within the city limits, splits into a one-way pair after crossing the Chadakoin River.

The one-way pair remains intact through downtown to Prendergast Avenue, where NY 394 comes back together and shifts south onto Fourth Street.

NY 394 continues eastward, passing into Cattaraugus County and meeting the Southern Tier Expressway at exit 15 by way of Schoolhouse Road.

The two highways follow parallel routings for an additional 1.5 miles (2.4 km) to exit 17 on the expressway (at the hamlet of Steamburg), where NY 394 terminates.

In 1749, an expedition under the command of Pierre Joseph Céloron de Blainville landed at the mouth of Chautauqua Creek on Lake Erie with the intent of claiming the Ohio Valley for the French.

[17] Construction began on a new limited-access highway through Cattaraugus and Chautauqua counties (part of the modern Southern Tier Expressway) in the mid-1960s.

[22][23] The concurrency was only temporary as NY 17 was realigned to follow the Southern Tier Expressway from Bemus Point to Mina once that segment was completed in the early 1980s.