Informal music learning, pioneered by Green (2002, 2006, 2017), presents an alternative approach that integrates students' interests in popular music, bridging the informal and traditional styles of Western music education in schools. We conducted a scoping review adhering to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines to investigate informal music learning. Our scoping review encompasses 28 empirical, peer-reviewed articles published from 2006 to 2023. First, we analyse the diverse contexts, methodologies and geographic locations in which informal music learning has been investigated. Second, we explore how different stakeholders perceive and engage with informal music learning in various educational settings. Lastly, we summarise the implications derived from the analysed studies on informal music learning. Our findings reveal that across various educational contexts, informal music learning has consistently demonstrated its positive impact in motivating students. We also find that researchers have extended their investigations from programme reform to exploring pupil and teacher's musical identities. Recommendations for future research include exploring informal music learning in ensembles and elementary music classrooms and employing quantitative or mixed methods to assess its effectiveness and impact.