His grandfathers were the South Street merchant Lockwood DeForest and the New York Stock Exchange's first President, Robert Doughty Weeks.

He attended primary school in New York City and Easthampton, Massachusetts, before graduating from Yale College with honors in 1870.

He led the Hackensack Water Company from 1881 to 1926[3] and served as its president for at least 15 years, and as a trustee or director of multiple other corporations.

[5] DeForest married Emily Johnson, the oldest daughter of Central Railroad of New Jersey President John Taylor Johnston, in 1872 and had four children.

[3] Robert belonged to organizations including the Century, University, Grolier, Jekyll Island, and Seawanhaka Yacht Clubs.