He attended Peekskill Military Academy and Charlottesville University Mechanics Institute, and then became a carpenter. During the American Civil War, he fought with the 71st New York Volunteers. After the war he engaged in the manufacture of stoves in Peekskill.
Robertson was a member of the New York State Assembly (Westchester Co., 3rd D.) in 1882.
He was a member of the New York State Senate (15th D.) in 1894 and 1895, and was a member of the Lexow Committee.
He was President of the Village of Peekskill from 1897 to 1899.
He died on September 17, 1906, at his home in Peekskill, New York, "after a long illness, from paralysis", and was buried at the Hillside Cemetery in Cortlandt Manor.
