Peaches Geldof died from an overdose of heroin - the drug that also killed her mother Paula Yates - the coroner presiding over her inquest is expected to announce today.
A full inquest will take place in late July, reports the Guardian.
Sarah Ferguson and Nick Grimshaw were among the guests who paid tribute to Geldof at her funeral at St Mary Magdalene and St Lawrence church in Davington, Kent on Easter Monday.
The service was held at the same church in which she married husband Thomas Cohen in 2012 and where her mother Paula Yates' ashes were scattered in 2000.
After news that Peaches had passed away was confirmed, her father Bob Geldof said in a statement, "We are beyond pain. She was the wildest, funniest, cleverest, wittiest and the most bonkers of all of us."
Her husband Cohen said, "My beloved wife Peaches was adored by myself and her two sons Astala and Phaedra and I shall bring them up with their mother in their hearts every day."