The Lithuanian band will perform its song "Discoteque" after Bulgaria’s act and before Ukraine’s performers.
The Roop will compete with acts from 25 countries.
Lithuania has been the only Baltic country to qualify for the Grand Final of the 65th edition of the contest.
Bookmakers’ favorites to win the contest include Italy and France.
The Roop won Lithuania's national Eurovision selection last year, too, but the contest was cancelled due to the pandemic.
The 65th edition of the Eurovision Song Contest is being held in Rotterdam under strict coronavirus precautions.
Lithuania debuted in the contest, held annually since 1956, in 1994.
The country's best-ever Eurovision finish came in 2006 when LT United with their song "We are the Winners" placed sixth in Athens.