He was elected in 2014 to an at-large seat on Forsyth County School Board and spent two years on the board. In August 2015, Johnson filed papers to run for the position of North Carolina Superintendent of Public Instruction in 2016. In the November 2016 election, Johnson won with 50.6% of the vote, narrowly defeating the Democratic incumbent June Atkinson. Atkinson had served 11 years in the post and had worked for the department for about 28 years before becoming superintendent. She was the longest-serving state superintendent in the nation. Johnson became the first Republican to win the position in more than a hundred years. Johnson has opposed the idea of arming North Carolina teachers with guns, an idea promoted by Donald Trump and others. However, Johnson does favor more funding for school resource officers. In 2019, Johnson supported a 5% salary increase for North Carolina teachers by 2030, which would allow the average teacher salary in North Carolina to approach the median 2019 household income in North Carolina. He also proposed to increase funding for textbooks and digital media. As state superintendent, Johnson had a combative style; when he later announced his candidacy for the Republican nomination for lieutenant governor, he described himself as "in the trenches fighting the deep state in state bureaucracy." Johnson's relationship with the North Carolina State Board of Education has been often tumultuous. In 2016, shortly after Johnson's election, the North Carolina General Assembly enacted legislation in a special session to shift power from the State Board of Education to the state superintendent, granting Johnson power over the $10 billion North Carolina education budget. This prompted a legal battle, culminating in a North Carolina Supreme Court decision, in which both sides claimed a partial victory. In January 2020, Johnson and the board clashed over Johnson's signing of a $930,000 "emergency contract" for a Web-based reading assessment tool designed for kindergartens through 3rd graders in support of the state's "Read To Achieve" program. The value of the emergency contract was just below the dollar threshold requiring board approval, and a rival company that lost the contract subsequently filed a bid protest, contending that the software selected did not meet state requirements. In February 2020, Johnson used a state database to send 540,000 text messages and 800,000 emails to parents and teachers, polling them about Common Core. The text message read, "NC Superintendent Johnson wants to remove Common Core from NC schools. Do you? Complete this survey to guide our work." The mass text prompted a number of teachers and parents to file complaints against Johnson with the State Ethics Commission, alleging a politically motivated use of state resources to send a campaign-style message that coincided with the beginning of early voting in the North Carolina primary elections, in which Johnson was on the ballot in the race for the Republican nomination for lieutenant governor. Johnson's department defended the use of a state database to send the texts and emails. Johnson was state superintendent during the COVID-19 pandemic in North Carolina, when schools were closed to control the spread of the virus. Johnson chose not to seek reelection as state superintendent, instead filing papers in December 2019 to seek the Republican nomination for North Carolina lieutenant governor in 2020. In the March 3, 2020 Republican primary, Johnson lost, coming in third place.
