A by-election was held in French Guiana's 2nd constituency on 4 March 2018, with a second round on 11 March as no candidate secured a majority of votes in the first round. The by-election was called after the Constitutional Council invalidated the election of Lénaïck Adam, candidate of La République En Marche! (REM), in the June 2017 legislative elections on 8 December 2017. As in June 2017, Adam narrowly defeated Davy Rimane, supported by La France Insoumise, in the second round.