Mendham Borough (07945) was incorporated in 1906 from portions of Mendham Township. At the time, people who lived in what became the Borough, wanted public water and sewer services, while those who lived in the rural areas of the Township, felt it was cost prohibitive. The Borough has a charming downtown with shops and restaurants. The community has a total area of 6 square miles and has approximately 1,830 housing units. There is a mixture of housing from historic homes to $3+ million palatial estate homes. Housing developments and neighborhoods include: Cosma Lake, Hidden Orchard, Tempe Wick, Deer Ridge, Deerfield, Springhill, Balbrook, and Horseshoe Bend. The Phoenix House was constructed in the early 19th century, purchased in 1820 by William Phoenix for use as an inn, and then used from 1857 to 1907 by his daughters as a boarding house. The building is a fine example of the Federal style, with Greek Revival-style porches added in 1840.

Residents can use County Highway 510 for their eastbound commute. The train station in Morristown is located to the east.

Mendham Borough students attend Hilltop Elementary School (grades K-4) and Mountain View Middle School (grades 5-8). Mendham Township students attend Mendham Township Elementary School (grades K-4) and Middle School (grades 5-8). Both Mendham Township and Mendham Borough students in grades 9-12 attend West Morris Mendham High School, which is located in Mendham Borough and is part of the West Morris Regional High School District.