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."
- Family's home floods three times in just four days following thunderstorms
- What to do if you've got an Ikea chest of drawers that isn't fixed to the wall
- Extra-large coffin of helicopter crash victim inspires sister to shed eight stone
- I knew Ben Butler would kill daughter Ellie, says ex-girlfriend
- Sadiq Khan demands more devolution for London in Brexit aftermath