The memory of PC Palmer – who was murdered trying to stop the rampage of Westminster terrorist Khalid Masood – will be celebrated with the largest-ever gathering of police officers in the UK’s history.
Officers are expected to line the route to Southwark Cathedral for the service, which begins at 2pm.
An estimated 50,000 members of the public are also expected to attend the memorial.
Metropolitan Police Federation chairman Ken Marsh described the response as “incredible”.
He said: “The public are as appalled by what happened as the police.
The late police officer's memory will be celebrated with a memorial in London
More than 5,000 police officers are expected to attend
“At times they can be our biggest critics but when something like this happens they come together with us, because they don’t like someone hurting one of their own.
“I can’t recall an occasion like this in regard to the number of officers who will be there, but we must not lose sight of the fact that it is a family funeral.
“It is for Keith’s family, and we have made sure we have down everything his wife wants because, first and foremost, it is for her to mourn her husband.”
Around 40-50,000 civilians are also expected to pay their respects
Get Quotes on Home Insurance
PC Palmer was stabbed to death in the terror attack on March 22 trying to stop extremist Masood breaking into the Palace of Westminster with two knives.
The late officer fought Masood unarmed.
Victims of the Westminster terror attack Fri, April 7, 2017
The Westminster attack has now killed six people
SWNS.com 1 of 11
Andreea Cristea died of her injuries following the Westminster terror attacks
The deranged extremist killed five others before he was shot dead by an armed officer.
Andrea Cristea, the fifth victim of the attack, died in hospital on Friday after falling into the River Thames during the incident.