First presidency
When forming her cabinet, Heine appointed Alfred Alfred Jr. as Minister of Resources and Development, Mike Halferty as Minister of Transportation and Communication, Thomas Heine as Minister of Justice, Wilbur Heine as Minister of Education, Kalani Kaneko as Minister of Health, Amenta Matthew as Minister of Internal Affairs, Tony Muller as Minister of Public Works, John Silk as Minister of Foreign Affairs, Brenson S. Wase as Minister of Finance, Mattlan Zackhras as Minister in Assistance. Heine did not retain any members of Nemra's cabinet except for Halferty, who had resigned days before Nemra's government was dissolved. David Paul had been her first choice for minister of finance, but he declined; he later became Minister in Assistance in November 2017. Alfred Alfred Jr. resigned in January 2018. Mike Halferty and Thomas Heine later traded their positions, and Halferty was eventually relieved by President Heine in favor of Jack Ading on 28 June 2018.
Heine implemented a policy within her government that issues were to be addressed by the cabinet collectively instead of unilaterally by individual ministers, and that decisions were to be made based on data instead of social pressure. In the first year of her presidency, Heine introduced her governing program, Agenda 2020: A Framework for Progress. Because of the nation's lack of political parties, this acted as a unifying platform for the cabinet. Heine was reluctant to make changes in her personal life after assuming the presidency. She accepted that she would be routinely accompanied by bodyguards and that her husband would have to do their shopping, but she chose not to move to a different house or drive a government car.
When the first case of Zika virus in the Marshall Islands during the 2015–16 Zika virus epidemic was confirmed, Heine declare a state of health emergency. By April 2016, the Marshall Islands faced a severe drought, prompting Heine to declare a state of disaster. Heine was involved in the creation of the Pacific Women Leaders Coalition in 2017 as a means for female politicians in the region to collaborate on gender issues and other causes. She supported the creation of the government-sponsored Miss Marshall Islands pageant, believing it to be a path for women to adopt leadership positions. She also implemented a program to provide small business loans for women. Heine had the National Nuclear Commission created in 2017. Following a 2017 Marshallese study that found a correlation between poverty and stunted growth in children, Heine successfully requested funding for a childhood development program from the World Bank. The program launched in 2022, after her presidency ended. In May 2018, Heine signed an air transport agreement with Papua New Guinea.
A dispute in the legislature arose in 2018 regarding whether Rongelap Atoll should be designated as a special administrative region. Heine opposed the proposal, considering it to be unconstitutional. This led to a motion of no confidence in Heine's government, which she blamed on Chinese influence. On 12 November 2018, she survived the motion with the outcome in votes being 16–16, falling short of the 17 votes needed. A later investigation by the United States government found that two prospective investors had bribed several officials to support the motion, and that its failure prompted discussion of "revenge".
Heine was Chancellor of the University of the South Pacific (USP) from 1 July 2019 to 12 January 2020. She negotiated the Kora fund with Taiwanese president Tsai Ing-wen in 2019 in which Taiwan funds women's businesses in the Marshall Islands. Heine was president during the 2019–2020 dengue fever epidemic, and she issued a state of health emergency on 6 August 2019. She supported the decision to abolish non-resident citizen voting in the 2019 election, arguing that without structure, it would let people rig the votes.
