Born in Calhoun in western Ouachita Parish, Mills attended public schools and then enrolled at Louisiana Tech University in Ruston, Louisiana State University in Baton Rouge, Northwestern State University, then Louisiana Normal College, in Natchitoches, and Spencer Business College in New Orleans.

From 1921 to 1932, Mills taught school in Mer Rouge in Morehouse Parish.

He was also engaged in agricultural pursuits, cattle raising, real estate, and oil.

He unseated Representative Riley J. Wilson of Catahoula Parish in the 1936 Democratic primary.

In 1942, however, he was himself defeated for renomination by Charles E. McKenzie, a native of DeSoto Parish who had relocated to Monroe.