He attended the public schools, graduated from Yale Law School in 1894, was admitted to the bar and commenced practice in New Haven.
Donovan joined the Connecticut Army National Guard for the Spanish–American War, and served as captain of Company C, 2nd Regiment from 1897–1903. Afterwards he was active in the United Spanish War Veterans. From 1904 to 1906 he was Secretary of the New Haven Civil Service Commission.
Donovan moved to New York City in 1910 and continued to practice law.
From 1911 to 1913 he served as a state Special Deputy Attorney General. In 1918 he was elected to the 65th Congress in a special election to fill the vacancy caused by the resignation of George Murray Hulbert.
Later in 1918 he was elected to a full term in the 66th Congress, and he served in the House from March 5, 1918 to March 4, 1921. He was an unsuccessful candidate for reelection in 1920.
From 1923 to 1924 Donovan served as Deputy Attorney General for the New York State Department of Labor.
He then resumed the practice of law in New York City until retiring in 1936. In retirement Donovan resided in Stony Creek, Connecticut. He died in Stony Creek on November 2, 1949 and was buried at Saint Bernard"s Cemetery in New Haven.
A Democrat, Donovan was a member of the Connecticut House of Representatives from 1901 to 1903, and New Haven City Auditor from 1902 to 1904.