The technical error has directed people searching for the national park more than 150m (241km) away to a location between Chelsea and Knightsbridge.
Brecon Beacons National Park Authority posted the image online with the caption: "We have now moved. Londoners get an upgrade thanks to Google Maps."
Chief executive John Cook joked: "Well the move has come as a bit of a shock to us all."
He added: "I'm sure it will come as good news to Londoners who want some fresh mountain air on their doorstep.
"The truth is we are only three hours away from London - don't rely on your sat-nav or Google Maps - just head to Bristol on the M4, cross the bridge, ask a local and they'll know exactly where to find us."
A glitch on Google Maps has located the Brecon Beacons in the heart of London.