Christopher Langley, from Pontypridd, teamed up with publican James Lovegrove to put the paintings together.
The Campaign for Real Ale (Camra) said two pubs close every week in Wales.
Mr Langley has painted 13 so far, and hopes to complete another 20 over the coming months - saying there is "so much history that could be lost".
Pubs featured so far include The Vulcan - recently saved by St Fagan's Museum - as well as the York Hotel, the Pantmawr Inn and the Glendower.
"It has broadened my awareness," Mr Langley said.
"I was never brought up around pubs, but meeting James and talking to him about the pubs of Cardiff has really opened my eyes to that culture.
"There is so much history there that could be lost. This is a way of preserving and sharing that history."
The paintings are done from drawings or photographs if the buildings no longer exist.
"I had never appreciated the architecture of pubs before.
"But when you stand there and paint them you see just how much effort has gone into creating these places."
An artist is hoping to preserve the history of Cardiff's pubs through an exhibition.