The Irish musician, originally from Limerick, led the band to international success in the 90s with singles including Linger and Zombie.
A statement from her publicist said: "The lead singer with the Irish band The Cranberries was in London for a short recording session.
"No further details are available at this time."
A Metropolitan Police spokesperson said the police were called to a hotel in Park Lane at 09:05 GMT on Monday, where "a woman in her mid-40s" was pronounced dead at the scene.
The death is, at this stage, unexplained.
Her current band mates in The Cranberries - Noel Hogan, Fergal Lawler, and Mike Hogan - paid tribute to the lead singer on social media.
The message said: "She was an extraordinary talent and we feel very privileged to been part of her life from 1989."