Barnet Council has confirmed the cancellation of the poll in Colindale ward following the death of Green Party candidate Jessica Yorke.
As is required by electoral law, a new election will be held in the ward within 35 working days of the May 22 election date.
It is understood Jessica passed away several days ago following a long battle with cancer.
Polling for the European Parliamentary elections will still go ahead and all polling stations in the ward will be open as planned.
All the other candidates in the Colindale ward local elections will remain nominated.
Chief executive of Barnet Council and returning officer Andrew Travers said: “It is with great sadness we have learned of the death of a local candidate following a serious illness.
“My thoughts go out to their family at this difficult time. I will be announcing a new date for the election as soon as possible.”