Senate Johnson is chair of the Senate Insurance and Commerce Committee. He is a member of the Senate Judiciary Committee, the Joint Energy Committee, the Senate Efficiency Committee, the Joint Budget Committee and the Arkansas Legislative Council. During the 95th General Assembly Senate Johnson is serving his second term as the Majority Leader .

In the 94th General Assembly, Senator Johnson sponsored legislation to consolidate agriculture boards and commissions. He also sponsored legislation that dealt with the filing date to the Tax Appeals Commission and to amend the appointment procedure for the Tax Appeals Commission.

During the 2021 regular session Senator Johnson sponsored legislation to mandate inspections of abortion facilities, to create an Independent Tax Appeals Commission and to limit drag racing on a public highway. He was the Senate sponsor of legislation to cut in half the annual registration fee on hybrid vehicles.

In past sessions, Senator Johnson sponsored legislation which requires welfare recipients to undergo testing for illegal drugs in order to qualify for benefits. He sponsored a change in how the wealth index is calculated for school facilities funding.

He was the Senate sponsor of legislation creating the Arkansas Future Grant Program.

Senator Johnson has sponsored "revolving door" legislation that requires legislators to wait at least two years after their retirement from the General Assembly before registering as a lobbyist. The law prohibits former legislators from working at an educational cooperative or local area agency on aging until two years after they leave the legislature. He has co-sponsored major tax relief legislation, pro-life laws and legislation that reduces the fees for concealed carry permits.

Senator Johnson has sponsored bills to create options for issuing a standard teaching license for nontraditional licensure programs, to limit the number of professional development days required for teachers and to strengthen background checks for public school teachers and employees.

Senator Johnson is a farmer. Before his election to the Senate, he had served as an alderman in Corning. He was born in Poplar Bluff, Missouri, and graduated from Arkansas State University. He and his wife, Tricia, have a son and a daughter. Senator Johnson and his wife are members of the First Baptist Church of Corning.