A member of the Republican Party, he served as chairman of the Montana Public Service Commission where he left office in January 2023.
He also served as a district representative for Congressman Ron Marlenee and worked as an agricultural extension agent.
Johnson withdrew from the race for Public Service Commissioner in 2010 after pleading guilty to driving under the influence in Broadwater County.
Johnson was elected Public Service Commissioner for District 5 in 2014, defeating Democrat Galen Hollenbaugh, and was chosen to be chairman of the commission by his colleagues.
[4] He announced his candidacy for Governor of Montana in the 2016 election, but withdrew from the race in January citing fundraising concerns and commitment to his duties on the Public Service Commission.