In 1897, McMillin sought the U.S. Senate seat left vacant by the death of Isham G. Harris.
Failing to garner any support, he then sought and successfully obtained the Democratic nomination for governor the following year in the race to succeed popular governor Robert Love Taylor.
 McMillin won by a large margin on election day, with 105,640 votes to 72,611 for the Republican candidate James Alexander Fowler, 2,428 for Populist candidate W.D. Turley, and 1,722 for Prohibition candidate R.N. Richardson.

By the time McMillin ran for reelection in 1900, the state's Republican Party had come under the control of Congressman Walter P. Brownlow.
 Seeking to unseat McMillin, Brownlow and his faction nominated Congressman John E. McCall as the party's candidate for governor.
 While the party ran a strong campaign, McMillin was easily reelected, winning 145,708 votes to 119,831 for McCall.

During his two terms, McMillin implemented a number of progressive measures.
 He signed legislation authorizing counties to establish high schools and school boards, and instituted a property tax to pay for school textbooks.
 In 1901, he signed legislation aimed at reducing child labor by increasing the state's minimum age for employment from 12 to 14.
 He also finalized the state's boundary with Virginia, and set up a sinking fund to reduce the state debt.
In 1897, McMillin sought the U.S. Senate seat left vacant by the death of Isham G. Harris. Failing to garner any support, he then sought and successfully obtained the Democratic nomination for governor the following year in the race to succeed popular governor Robert Love Taylor.  McMillin won by a large margin on election day, with 105,640 votes to 72,611 for the Republican candidate James Alexander Fowler, 2,428 for Populist candidate W.D. Turley, and 1,722 for Prohibition candidate R.N. Richardson.
By the time McMillin ran for reelection in 1900, the state's Republican Party had come under the control of Congressman Walter P. Brownlow.  Seeking to unseat McMillin, Brownlow and his faction nominated Congressman John E. McCall as the party's candidate for governor.  While the party ran a strong campaign, McMillin was easily reelected, winning 145,708 votes to 119,831 for McCall.
During his two terms, McMillin implemented a number of progressive measures.  He signed legislation authorizing counties to establish high schools and school boards, and instituted a property tax to pay for school textbooks.  In 1901, he signed legislation aimed at reducing child labor by increasing the state's minimum age for employment from 12 to 14.  He also finalized the state's boundary with Virginia, and set up a sinking fund to reduce the state debt.
Benton McMillin