The Tokyo 2020 Olympic champion was diagnosed with an unspecified stress fracture after finishing second in the Valencia marathon in December.
That delayed the start of her training for London, and the 32-year-old Kenyan has now told race organizers she must withdraw.
Jepchirchir won the 2024 London Marathon in a women ‘s-only world-record time of two hours 16 minutes and 16 seconds.
“I was only able to resume training in late January,” she said in a statement.
“I know that to be competitive at the London Marathon, you have to be at your top level, and despite my best efforts, I’m just short of that due to my lack of training.”
Jepchirchir missed last year’s event in London because of an ankle injury.
The 2024 Olympic champion Sifan Hassan had already withdrawn from this year’s race on 26 April, having suffered an Achilles injury.
