Dennehy's first opened its doors in 1957 on Cornmarket Street (known to Corkonians as the Coal Quay) in the historic old town of Cork City in a building dating back to 1760. Founded by Maura Dennehy, the bar was passed on to her son Con Dennehy and wife Mary in 1993. Still in the family today the bar is currently run by Mary Dennehy and her sons.

The area has a long history of street trading dating back centuries, a place where generations of Cork’s citizens bought food and other articles. Working class Irish women survived as street traders on the Coal Quay, selling fruit, vegetables and second hand clothing. Locally they were known as ‘the Shawlies’ because of the distinctive, traditional black shawls they wore on the streets and they were a common sight in Cork City into the 1970s.

Cork character and legend Kathy Barry (1909-82) who is famed in the Irish folk song 'Boys Of Fairhill', visited Dennehy’s Bar three times a day for a small whiskey and a glass of stout, and ran a "shebeen" to the back of the premises. A "shebeen" was originally an illicit bar, speakeasy or club where alcoholic beverages were sold without a licence.

One of the most famous and final photographs of Kathy Barry which adorns many Irish bars around the world was in fact taken at Dennehy's in 1980 by Irish Examiner photographer, the late Michael Olney. An original print hangs framed on the wall of Dennehy's.

Amid developments, progress and technology, Dennehy’s has remained true to the tradition and heritage of what a real traditional Irish pub should be, while still embracing new light through old windows.