East Barnet ward councillor Olwen Evans died on Christmas Day at the age of 72 after a long battle with cancer.
Miss Evans, of Summit Way, Southgate, represented the ward from 1978 to 1994 and then from 1998 until her death.
She held numerous posts in council during her political career and, despite her illness, continued working as a councillor and chairwoman of two overview and scrutiny committees, almost right up to her death.
Her cousin, Peter Jones, said: "She was very much a constituency councillor."
"She had cancer for 14 years but the way she carried on in spite of serious illness and treatment is quite remarkable."
Council leader Mike Freer hailed Mrs Evans' indomitable spirit'.
He said: "Councillor Evans was a stalwart of the council having served the ward of East Barnet for 24 years.
"She played a full role in the council and undertook her duties with great diligence, showing a deep interest in environmental matters long before it was fashionable.
"Councillor Evans was a public servant of the old school, hard-working, diligent and full of integrity. She will be greatly missed."
Brian Coleman, London Assembly chairman and fellow Barnet councillor, said: "When the chips were down Olwen was there; you could always rely on her.
"She was a fighter for the people of East Barnet, to whom she was absolutely devoted."
Labour group leader Councillor Alison Moore also paid tribute to her.
She said: "She was very hard working and stood her ground on matters of principle within her ward."
Miss Evans' funeral was due to take place this afternoon at East Barnet Parish Church, Church Hill Road, East Barnet.
A by-election will be held in East Barnet in the next three months at a date yet to be set.