Colts Neck Township is a township in Monmouth County, New Jersey, United States. As of the 2010 United States Census, the population was 10,142, reflecting a decline of 2,189 from the 12,331 counted in the 2000 Census, which had in turn increased by 3,772 from the 8,559 counted in the 1990 Census.What is now Colts Neck Township was established by an act of the New Jersey Legislature as Atlantic Township on February 18, 1847, from portions of Freehold Township, Middletown Township and Shrewsbury Township. The name was changed to "Colts Neck Township" as of November 6, 1962, based on the results of a referendum held that day.