In 1858, Birney was nominated as a Republican candidate for the Michigan Senate. At the time the senate district was regarded as a stronghold of the Democratic Party, thus it was seen as a significant achievement that Birney garnered all of the votes in the district within Bay County except for five. He served a single term in the Senate representing the Saginaw district. While in the Senate, Birney was chairman of the committee on public instruction and a member of the judiciary committee.