O.H.P. Brewer was born at Webbers Falls, Indian Territory, to Cherokee parents who had emigrated to the area from Georgia in 1838. Brewer was educated in the tribal public schools, Cherokee National Male Seminary, and graduated from the University of Arkansas. He returned home to work on his parent’s plantation at Webbers Falls before being elected to the Cherokee Senate, in which he served on the committee on education. He later became a member of the Cherokee Board of Education and served as the group’s president for six years.

In 1906, Brewer became a member of Oklahoma’s Constitutional Convention and served on a number of committees, including that of chairman on the committee of education and as a member of the committee on public buildings. In 1910, he returned to his home in Muskogee and was admitted to the bar and served as a district judge in the Eighth District before being appointed postmaster at Muskogee in 1913.