The victim ordered what she believed to be cannabis “gummies” last Tuesday which were delivered to her home in Ilford.
The woman and a 21-year-old friend each ate one sweet and both immediately felt unwell.
They were rushed to hospital after police and paramedics were called to the address in South Park Drive at 11.30pm that same day.
The 23-year-old victim, whose identity has not been released, died on Saturday.
Her friend has been released from hospital after treatment.
Officers said they are awaiting the results of a special post-mortem and tests on the sweets.
An urgent probe is also underway into a potentially linked case in which a woman was hospitalised earlier in March after eating a cannabis sweet in Tower Hamlets.
She has since been discharged and enquiries are ongoing to establish whether this sweet was part of the batch of sweets associated with the death in Ilford.
Chief Superintendent Stuart Bell of the Met’s East Area BCU warned the public against “taking any illegal substances, including those packaged in the form of cannabis sweets”.
“Please do not buy or consume these products,” he said.
“They are illegal and, because of the child-friendly packaging, they can pose a risk of accidental consumption. The particular batch of sweets were contained in packaging featuring ‘Trrlli Peachie O’s’ branding. It has not been confirmed at this stage where the sweets were manufactured.
“Drug dealers harm communities and risk the safety of individuals. We will take positive action to target those engaged in this activity as well as those found in possession of these substances.”
Anyone with information about people selling illegal products such as cannabis sweets has been urged to contact police or Crimestoppers.
A man was arrested by police on Friday, April 1.
He was found to be in possession of a large quantity of cash and what were believed to be edible cannabis products, said police.
The man was charged the following day with possession with intent to supply Class B synthetic cannabinoid, being concerned in the supply of a synthetic cannabinoid, and possession with intent to supply a psychoactive substance.