Grosvenor was a member of the Kenosha Common Council from 1921 to 1922. From 1923 to 1933, he was a member of the Kenosha County, WisconsinBoard, serving as its Chairman from 1927 to 1929. He was a member of the assembly from 1933 until his resignation in 1939. He was serving as the Kenosha postmaster at the time of his death. He was a Democrat.