The singer played the show as part of the Arthur's Day celebrations, marking the anniversary of Arthur Guinness signing the 9,000-year lease on the famous Dublin brewery.
Jones later played a second set at Senate House, alongside Wretch 32, VV Brown and Razorlight.
"The Wheelbarrow in Camden has well and truly been rocked!" Jones said on Twitter.
"Thanks all for coming an enjoy the beautiful black stuff #ArthursDay."
Pub landlord Ellis Billington said: "The surprise performance provided a unique experience for the locals thanks to Guinness.
"I was speechless when he walked in, as were most of the punters!"
A total of 28 pubs in and around the Soho area were celebrating Arthur's Day, but it was not known which venue Jones would play his secret gig.
He played for a crowd of just 100 people at the Camden venue after arriving at 6pm.
Arthur's Day was launched in 2009 to mark the 250th anniversary of the Guinness lease signing and this year marks the first time official celebrations have been held in Great Britain.