Ransier was born a free person of color in Charleston, South Carolina.

He worked as a shipping clerk until, after the Civil War, he was appointed as state registrar of elections in 1865.

In the late 1860s, he was hired by African Methodist Episcopal Church bishop and fellow future congressman, Richard H. Cain, to be an associate editor of the South Carolina Leader (renamed the Missionary Record in 1868), along with another future congressman, Robert B.

He was elected from South Carolina's 2nd Congressional District to the 43rd United States Congress, where he fought for the Civil Rights Act of 1875.

After leaving Congress in 1875, Ransier was appointed by Republicans as a collector for the Internal Revenue Service.