The song is set in common time and has a tempo of 120 beats per minute. While it is played in the key of C major and has backing piano and guitar sounds, "Alfie" also uses a sample from Sandie Shaw's 1967 Eurovision Song Contest winning song "Puppet on a String". In an interview with Pitchfork Media, Allen stated that the song's lyrics describe her younger brother, Alfie Allen. She further explained:When I wrote "Alfie", nobody really knew who I was. At first he was really upset about it, because he thought that I was just pointing out all of his bad points and attacking him. I thought it was really flattering [Laughs]. I thought he'd be really, really happy because it proved to him how much I loved him, that I care about him, and I want him to do something with his life. I suppose his paranoia — induced by smoking so much weed — made him think, "Why are you trying to be mean?"