The Cooper Union was founded in by Peter Cooper, an inventor and entrepreneur from a humble background, to provide educational opportunity to poor people in the neighborhood. Cooper is said to have wanted to offer "education that was as free as the air we breathe and the water we drink." In the beginning, Cooper Union offered adult education in night classes on the subjects of applied sciences and architectural drawing, as well as day classes for women on the subjects of photography, telegraphy, typewriting and shorthand.

Early board members included Horace Greeley and William Cullen Bryant.

During the Presidential election year of 1860, the college was the site of a notable address by an attorney from Illinois, then an undeclared candidate for the Republican Party's nomination. Abraham Lincoln's dramatic speech against slavery galvanized support for Lincoln in New York State, and contributed to his gaining the Party's nomination for the Presidency.