Martin R. Bradley was born at Newberry, Michigan, in 1888. While still a child, his family moved to Huron County. He attended Ferris Institute and Central State Teachers College, and then taught in rural schools in Huron County. In 1910 he went to Hermansville, Menominee County, as superintendent of schools, and remained in that position until 1914 when he became an agent for the Reliance Life Insurance Company. Mr. Bradley was also postmaster at Hermansville from 1914 to 1923.
A five-term Democratic member of the Michigan House of Representatives, Mr. Bradley was first elected for one term in 1922, and then was elected to four successive terms beginning in 1926. He was elected speaker of the House for the 1933-1934 session, the first Upper Peninsula representative to be so honored. A bill providing for creation of the Michigan Legislative Council was introduced under Mr. Bradley's sponsorship, and he served as chairman of the Council in 1933-1934. The bipartisan Council met between sessions to formulate a legislative program for submission to the next session.
In 1935 Bradley was appointed collector of customs for Michigan, a post to which he was reappointed several times. From this time on he made his home in the Detroit area, but maintained an active interest in matters relating to the Upper Peninsula.