The ribbon-cutting ceremony at Southside Community Centre was attended by Mr Cook's son Chris, Southside councillor Bob Cairns and Edinburgh MPs Alistair Darling and Nigel Griffiths.
Mr Cook, a former Foreign Secretary and Edinburgh councillor, died of a heart attack while hill walking last summer.
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Hide AdA fundraising drive among local residents in south Edinburgh quickly raised the 800 needed to pay for the bench.
Cllr Cairns told guests at the unveiling ceremony that Mr Cook had led the campaign to stop a road being built through the Meadows, which would have flattened hundreds of homes in the area.
Earlier this year, a lane where Livingston MP Mr Cook used to go horse-riding in the heart of his constituency was named after him.
Robin's Lane in Murieston is marked with three nameplates, one of which is mounted on a cairn.