The sign was hung on the outside of the giraffe house during lockdown, visible to ambulance crews who would park up outside the zoo during their lunch breaks.
It was removed just before the zoo reopened on April 15 and joins other items in the collection, including masks and even recordings of the capital’s empty streets during lockdown.
Senior Curator Beatrice Behlen said: “We are very honoured that ZSL London Zoo have donated their symbolic NHS sign to our ongoing Collecting COVID project.
“Throughout the last year, while London Zoo’s doors were closed, the sign was a source of great camaraderie for the local community and frontline NHS workers.
“It represents the many messages and acts of support that came from so many of London’s institutions to uplift, provide hope and connect Londoners over the past year.
“As part of our permanent London Collection the sign will help tell the story of London and Londoners from this time in a new and imaginative way, which is a priority as we look ahead to the opening of the new Museum of London in West Smithfield in the coming years.”
The museum, which is due to open in its new buildings in 2024, is also collecting lockdown dreams with recordings of conversations between volunteers and psychoanalysts discussing their possible meanings due to be displayed.