The Grassmarket venue, which opened 20 years ago, will be closed for eight to 10 weeks while the work continues, with a reopening planned for June.
Biddy Mulligans was part of a package of hotels and bars operated by Festival Group which became part of G1 Group in 2011. It also includes the Grassmarket Hotel, which is next door to Biddy Mulligans, and the nearby Three Sisters bar in Cowgate.
Donal Hurrell, general manager at Biddy Mulligans, said: “Biddy Mulligans has been the landmark Irish bar in the Grassmarket for 20 years, so we decided it was time to spruce things up to improve the experience we can offer to our many customers – including those who are still to make their first visit.”
He said that the bar’s ethos would remain the same despite the refurbishment. “We will still be famed for hosting an array of traditional and folk music, screening all the Gaelic games and of course our famous lively atmosphere.
“At this stage, we don’t want to give away too much about the changes we will be making but regulars can rest assured the ‘craic will still be ninety’.”
The origin of the bar’s name is the character of a Dublin widow created by Irish comedian and music hall singer Jimmy O’Dea in the 1930s and 1940s. She is perhaps best remembered for featuring in the song Biddy Mulligan the Pride of the Coombe.
G1 Group operates more than 40 venues in Glasgow, Edinburgh, Aberdeen, Dundee, Perth and St Andrews, ranging from restaurants, bars and clubs to cinemas and hotels.