East of Lancaster, the route runs through agricultural areas in Pennsylvania Dutch Country, serving Leola, New Holland, and Blue Ball, the latter location where it crosses US 322.

The route follows the Schuylkill River to West Conshohocken, where it has access to I-76 and I-476, before it continues southeast through Lower Merion Township to US 1, which there is running on the border between Montgomery County and Philadelphia.

PA 23 runs through farm fields with some residential and commercial development and crosses into East Hempfield Township at the Stony Battery Road intersection in the community of Oyster Point.

The road continues through development with some farmland, coming to bridges over the US 30 freeway without an interchange and Norfolk Southern's Columbia Secondary railroad line.

PA 23 comes to an interchange with the US 30 freeway, onto which it turns northwest for a brief wrong-way concurrency, with East Walnut Street heading northeast.

After the river, PA 23 splits from US 30 at a diamond interchange and heads northeast onto New Holland Pike, a three-lane road with a center left-turn lane.

[2][3] The road becomes West Main Street and curves northeast past residential and commercial development, crossing into the borough of New Holland.

PA 23 runs past more residences before entering commercial areas, passing to the south of Garden Spot High School and crossing back into Earl Township.

The route enters East Earl Township and runs past a mix of farmland, homes, and businesses as Main Street, crossing US 322 in the community of Blue Ball.

The road curves north-northeast through more rural areas, passing north of Conestoga Christian School before coming to an intersection with PA 10.

[6] The road crosses into Caernarvon Township in Berks County and intersects a ramp that heads north to provide access to northbound I-176 and from southbound I-176.

The route briefly gains a median again before it leaves Elverson for West Nantmeal Township, where it becomes Ridge Road and heads into a mix of farmland and woodland with some homes.

PA 23 continues through wooded areas with some fields and residences, passing to the south of the community of Saint Peters, where it crosses French Creek, and running to the north of Warwick County Park.

PA 23 curves southeast and crosses back into East Vincent Township and runs through more rural land with some residences, passing to the north of a golf course.

The route becomes the border between the borough of Phoenixville to the northeast and Schuylkill Township to the southwest and crosses French Creek before passing more businesses and intersecting PA 113.

The road continues east through fields and woods within Valley Forge National Historical Park, passing near the Friedrich Wilhelm von Steuben statue and Washington Memorial Chapel.

The route passes between residential high-rise buildings to the north and business parks to the south, narrowing into a two-lane undivided road and heading northeast.

The road turns southeast and crosses Trout Creek, running near more business parks and widening back to a four-lane divided highway.

PA 23 passes under the William F. Dannehower Memorial Bridge, which carries southbound US 202 over the route and the Schuylkill River to the north, and curves south into the borough of Bridgeport.

[2][10] PA 23 turns east onto Coates Street and forms the border between Bridgeport to the north and Upper Merion Township to the south.

The road curves southeast past more industry, narrowing to two lanes and crossing an Upper Merion and Plymouth Railroad spur at-grade before entering the borough of West Conshohocken.

The road heads through the community of Gladwyne, where it passes homes and a few businesses, before it crosses Mill Creek and makes a turn to the north and a curve southeast in forested areas.

[26] In 1992, the four lane-road connecting the east end of Chestnut and Walnut streets to the US 30 freeway in Lancaster was built, and PA 23 was rerouted off New Holland Avenue to follow Chestnut and Walnut streets east before continuing northeast on the four-lane road and northwest on the US 30 freeway over the Conestoga River to rejoin New Holland Pike.

[2] Despite the cancellation of the freeway, plans continued for capacity improvements on the PA 23 corridor in eastern Lancaster County due to increased traffic levels.

In 2010, the project was shelved after the Pennsylvania Department of Transportation (PennDOT) determined it needed the money to repair structurally deficient bridges.

[31] In July 2022, PennDOT broke ground on a project that extended Walnut Street northeast 1.2 mi (1.9 km) from the interchange between US 30 and PA 23 along the Goat Path alignment.

The extension of Walnut Street was built as a two-lane road along with a parallel bicycle and pedestrian trail called the Greater Lancaster Heritage Pathway.

Although PennDOT had secured funding for the spur, the start of construction was delayed for many years due to both local opposition to the location of the highway within Phoenixville, along with disputes over the design of the interchanges within the borough.

[37][38] In 2006, the Delaware Valley Regional Planning Commission proposed the "Intercounty Relief Route", a smaller-scale project that focused on the improvement of the corridor that would have been occupied by the Phoenixville Spur.

The project focused on the improvement of local roads instead of the construction of an expressway, while still providing a new crossing of the Schuylkill River, which was originally included with the spur route.