The Environment Agency has said the spill happened at Gorleston at about 7.20pm on Monday.
It is currently unclear how the spill occurred, but the Environment Agency has been contacted for comment.
The popular beach, near Great Yarmouth, draws in visitors from across the country and has even been named as one of the best in Europe.
As well as the current oil spill, this stretch of coast has recorded 17 sewage spills so far in 2026 after 149 days, averaging one spill roughly every eight days.
Anglian Water has previously said it is investing £1 billion between now and 2030 to tackle sewage-related issues.
The latest warning comes ahead of an amber heat-health alert from the UK Health Security Agency (UKHSA).
It is in place from 9am on Wednesday until 9pm on Sunday.
