The 46-year-old singer was founded dead in her room at the London Hilton hotel on Park Lane on Monday (15.01.18), and while her cause of death is not yet known, The Metropolitan Police have confirmed they are not treating it as suspicious.
Investigators are compiling a report to hand over to the local coroner’s office.
The Cranberries star was in the capital ahead of a recording session with Bad Wolves for a remix of the Irish group’s hit ‘Zombie’.
The police confirmed the mother-of-three’s passing, saying it was a “sudden death”.
A Metropolitan Police spokesman said: “Police in Westminster are dealing with a sudden death.
“Officers were called at 09.05hrs on Monday, 15 January to a hotel in Park Lane, W1. A woman in her mid -0s was pronounced dead at the scene.
“At this early stage the death is being treated as unexplained. Inquiries continue.”
A spokeswoman for the London Hilton added: “It is with deep regret that we can confirm a guest sadly passed away at the hotel on Monday 15th January.
“We offer our sincere condolences to their family at this difficult time. Team members acted swiftly to alert the Metropolitan Police and we are co-operating fully with their investigation.”
The Cranberries also informed their fans about Dolores’ sudden passing on their Facebook account.
They wrote: “Irish and international singer Dolores O’Riordan has died suddenly in London today. She was 46 years old. 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.
“Family members are devastated to hear the breaking news and have requested privacy at this very difficult time.”
Just last month, Dolores admitted she was “feeling good” after some performances ahead of the Christmas period.
She wrote on the band’s Twitter page: “Hi All, Dolores here. Feeling good! I did my first bit of gigging in months at the weekend, performed a few songs at the Billboard annual staff holiday party in New York with the house band. Really enjoyed it! Happy Christmas to all our fans!! Xo (sic)”