The Irish singer was found dead at her flat in Herne Hill of South West London last July. She was 56 years old.
In a statement, the coroner have called for an autopsy to be conducted, as no medical cause of death was given. They have also stated that post-mortem results would not be available for some weeks, after which a decision would be taken if an inquest into Ms O'Connor's death would be needed.
"This is to confirm that Ms O'Connor died of natural causes", a spokesperson for Southwark Coroner's Court said in their statement.
"The coroner has therefore ceased their involvement in her death. Any further enquiries should be directed to the Registrar at Lambeth", they added. "No further comments will be made".
Sinéad O'Connor came to prominence in 1990, after releasing her cover of Prince's song 'Nothing Compares 2 U', with O'Connor's version topping the charts worldwide.
The singer was laid to rest at a private funeral, which was attended by Irish musicians Bono and Bob Geldof, as well as President Michael D Higgins, back in August.
