Oldwick is an unincorporated community and census-designated place (CDP)[5] located within Tewksbury Township in Hunterdon County, in the U.S. state of New Jersey.

[6] The area is served as United States Postal Service ZIP Code 08858.

As of the 2000 United States census, the population for ZIP Code Tabulation Area 08858 was 177.

It has a mixture of Victorian, Federal, New England and Georgian style homes, and is protected by historic legislation.

[10][11] Oldwick is the corporate headquarters of the A. M. Best rating agency, and is the location of Mane Stream, formerly the Somerset Hills Handicapped Riding Center for adaptive riding and equine assisted therapy.