Tagelagi was first elected to the Niue Assembly at the
2008 Niuean general election. Following the
2014 Niuean general election he was appointed Minister of Infrastructure. He was re-elected at the
2017 Niuean general election, and subsequently served as Minister for the Environment, Natural Resources, Agriculture, Forestry and Fisheries. As Environment Minister he represented Niue at the
2019 United Nations Climate Change Conference, calling for rich nations to show greater ambition. He was re-elected in the
2020 Niuean general election and subsequently elected premier. After being elected he announced that his first priority would be investigating government finances. As Premier his government ratified the
PACER Plus regional trade agreement. During the
COVID-19 pandemic he negotiated a one-way travel-bubble allowing Niueans to travel to
New Zealand, and oversaw a vaccination program which saw Niue gain full herd immunity to the virus. In November 2021 he began a one-year term as Chancellor of the
University of the South Pacific. His tenure concluded in June 2022, and he was succeeded by
Tuimalealiʻifano Vaʻaletoʻa Sualauvi II. He was re-elected unopposed to the Assembly at the
2023 election. He was subsequently re-elected as Premier, defeating
O'Love Jacobsen 16 votes to 4. He appointed his Cabinet on 12 May 2023, the first gender-balanced Cabinet in Niuean history. ==Bowls career==