Fans watching music videos on YouTube and Vevo will be presented with cinema-style age certificates from Thursday.
The age ratings are part of a government-backed pilot scheme, which aims to protect children from unsuitable content.
It follows concerns over explicit videos by artists including Miley Cyrus, Robin Thicke and Rihanna.
Ratings will be decided by the British Board of Film Classification, with all three major record labels taking part.
This is the second phase of the pilot, which began as a behind-the-scenes trial in October.
Since then, record companies Sony, Universal and Warners have been submitting their videos to the BBFC for consideration.
The initial phase found that roughly 20% of all videos would receive a 12, 15 or 18 certificate.
However, labels were not required to submit videos they felt would not attract a rating, and only acts signed in Britain were scrutinised.
Among the songs deemed to require certification were Ellie Goulding’s Love Me Like You Do – from the soundtrack to Fifty Shades of Grey. The video, which contained several excerpts from the erotic thriller, was rated 15 by the BBFC for “strong sex references”.