Pc Palmer was stabbed to death as he tried to stop Khalid Masood after the terrorist crashed into the gates of the Palace of Westminster.
The cop will be honoured with a funeral at Southwark Cathedral on April 10, Scotland Yard confirmed on Wednesday.
Now, officers across the capital have been called upon to line the streets before the service in a moving tribute to their colleague.
Pc John Sutherland, from the Met Police, described the memorial as “one of the most powerful and moving things you'll ever see”.
A social media campaign under the hashtag #StandforKeith has been shared hundreds of times by serving and retired members of the force.
The post calls on all staff to “support the friends, family and colleagues of Pc Palmer by lining the streets of London during his funeral, to demonstrate support for and solidarity with all of those affected by the events that took place”.
It reads: “We need police officers, PCSOs and staff team 999 colleagues, service personnel and members of the public to join us as #WeStandTogether to remember our fallen colleague.”
The funeral will take place at 2pm followed by a private service at a crematorium.
The plans emerged as thousands of officers, members of the public and emergency services joined hands and marched across Westminster Bridge in tribute to Pc Palmer and three others killed in the attack.
PC Palmer's family say they had been “overwhelmed” by the “outpouring of love” for the police officer following the attack.
In a statement, they said: “We want to thank everyone who has reached out to us over the past few days for their kindness and generosity.
“The police have been a constant, unwavering support and this very difficult time.
“It has made us realise what a caring, strong and supporting family Keith was part of during his career with the police. We can’t thank them enough.
“We miss him so much, but we are also incredibly proud of Keith.”
Terrorist Khalid Masood ploughed a 4X4 into crowds on the bridge before crashing into the gates of the Palace of Westminster and stabbing PC Keith Palmer to death at 2.40pm last Wednesday.
Masood died after he was shot by police.