The pub, based in Carshalton Road, beat 27 others for the title in a competition organised by Paul Scully, prospective conservative MP of Sutton and Cheam.
More than 1,500 customers voted online with The Robin Hood and Gander Inn coming second and third.
Paul Scully said: "This competition has been really enjoyable to organise. The willingness with which customers participated shows how much residents cherish their local as a community hub.
"The Nightingale is a great example of a pub that draws in both local regulars and people from a good distance away, all of whom like good company, good music and a decent drink."
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