Due to his parents' financial troubles, Conor (Ferdia Walsh-Peelo), a teenager growing up in Dublin during the 1980s, has to switch from private school to a public school. He's bullied there both by other students and teachers. He finds one bright light in his life when he spots a beautiful girl who claims to be a model.

When Conor asks her to play a role in his rock band's video and she agrees, he quickly has to form a band. To his surprise, Conor discovers he has a talent not only for singing but also for writing songs. The band, called Sing Street, quickly becomes popular with the locals.