| Election Name: | March 2019 Tengatangi-Areora-Ngatiarua by-election |
| Type: | parliamentary |
| Country: | Cook Islands |
| Seats For Election: | Constituency of Tengatangi–Areora–Ngatiarua |
| Ongoing: | no |
| Previous Election: | 2018 Cook Islands general election |
| Previous Year: | 2018 |
| Next Election: | November 2019 Tengatangi-Areora-Ngatiarua by-election |
| Next Year: | Nov. 2019 |
| Election Date: | 18 March 2019 |
| Candidate1: | Te-Hani Brown |
| Image1: | Ind. |
| Party1: | Independent (politician) |
| Popular Vote1: | 80 |
| Percentage1: | 61.54% |
| Candidate2: | Nandi Glassie |
| Party2: | Democratic Party (Cook Islands) |
| Popular Vote2: | 50 |
| Percentage2: | 38.46% |
| Map Size: | 200px |
| MP | |
| Before Election: | Te-Hani Brown |
| Before Party: | Democratic Party (Cook Islands) |
| After Election: | Te-Hani Brown |
| After Party: | Independent (politician) |
| Turnout: | 99.2% |
A by-election was held in the Cook Islands constituency of Tengatangi-Areora-Ngatiarua on 18 March 2019.[1] The by-election was called following the defection of sitting MP Te-Hani Brown from the Democratic Party in January in order to support the government of Henry Puna, which triggered a by-election under election law.[2] [3] Brown ran as an independent with the support of the Cook Islands Party against Nandi Glassie, whom Brown had beaten in the 2018 Cook Islands general election.[4]
Although Brown retained her seat, Glassie filed a petition against her victory. He alleged that she had effectively bribed voters by covering the charge of a private aircraft to carry voters to vote on Atiu; Brown maintained that this did not constitute an offence.[5] Brown resigned in April 2019 during the process of the petition through the courts and although Glassie was allowed to challenge the election result, this was reversed on appeal.[6] Brown's seat was declared vacant in September 2019, triggering another by-election.[7]