"Andromeda" is set in the key of A minor and moves at a tempo of 130.101 beats per minute.

Ethel's death reminded Albarn of Bobby Womack, with whom Albarn had collaborated on Plastic Beach and Womack's The Bravest Man in the Universe, and who died in June 2014.

The sentimentality Albarn felt for lost family and friends was instrumental in the creation of "Andromeda", with Albarn commenting on the song's message: "Take the worst possible outcome, be brave, and remember all the goodness that preceded that... all the beauty that preceded that.

"[3] Albarn also stated that after a conversation with producer The Twilite Tone, he tried to evoke the sound of Michael Jackson's 1983 single "Billie Jean" from his iconic Thriller and Hall and Oates' single "I Can't Go for That (No Can Do)", from their album Private Eyes.

[3] Albarn also revealed that there were alternate versions of the song that he felt "Just didn't work out", such as a collaboration with English singer Rag'n'Bone Man, who appears on the song "The Apprentice" on the deluxe version of the album and a failed collaboration with French singer-songwriter Christine and the Queens, however, he ultimately opted for the collaboration with DRAM.