Portugal participated in the Eurovision Song Contest 2018 with the song "O jardim" written by Isaura. The song was performed by Cláudia Pascoal. In addition to participating in the contest, the Portuguese broadcaster Rádio e Televisão de Portugal (RTP) also hosted the Eurovision Song Contest after winning the competition in 2017 with the song "Amar pelos dois" performed by Salvador Sobral. RTP organised the national final Festival da Canção 2018 in order to select the Portuguese entry for the 2018 contest in Lisbon. After two semi-finals and a final which took place in February and March 2018, "O jardim" performed by Cláudia Pascoal and featuring Isaura emerged as the winner after achieving the highest score following the combination of votes from seven regional juries and a public televote.

The Eurovision Song Contest 2018 was the 63rd edition of the Eurovision Song Contest. It took place in Lisbon, Portugal, following the country's victory at the 2017 contest with the song "Amar pelos dois" by Salvador Sobral. Organised by the European Broadcasting Union (EBU) and host broadcaster Rádio e Televisão de Portugal (RTP), the contest was held at the Lisbon Arena, and consisted of two semi-finals on 8 and 10 May, and a final on 12 May 2018. The three live shows were presented by Portuguese television presenters Filomena Cautela, Sílvia Alberto and Catarina Furtado, and Portuguese-American actress Daniela Ruah, marking the first time that the contest was presented by four hosts.