Irish state broadcaster RTE said the singer died in London while there for a recording session.
Her publicist said her family were shattered by the news.
The Irish musician, originally from Limerick, led the band to international success in the 1990s with singles including Linger and Zombie.
In 2017 The Cranberries announced a tour including dates in Europe, the UK, and the US.
However, in May 2017, shortly into the European tour, The Cranberries had to cancel the remainder of the European dates as a result of O'Riordan's health issues.
