The firm has bought what used to be Swizzlestick Bars’ ‘Clause’ on Lovat Lane, and expects to open the new Dirty Martini in October after a £1m refurbishing and rebranding programme.
Monument will join the brand’s other City site at Bishopsgate, which opened late last year.
CEO Scott Matthews said: “This is an exciting time for our company; the success of our Bishopsgate and West End bars has been significant and we’re certain the new site will enhance our presence, profile and profits across premium areas of the Capital’s business district.
“We have already identified our next key target areas for growth and plan to add several more units in the near future.”
Like-for-like sales for Dirty Martini are up by over 17 per cent year to date.
CG hopes to have 15 sites across its four brands (Dirty Martini, Tuttons, Bitter Sweet and Fire & Stone) by the end of 2016.