The office will grow to 20 staff by the end of 2008.
The bank advises regional clients on international mergers and acquisitions deals and assists them with equity capital raising outside the region.
Its clients tend to be large, regional companies. They include the Abu Dhabi Investment Authority, which invested $7.5bn in the bank, equivalent to a 4.9 per cent stake, at the end of November.
Citigroup established its investment banking business in the DIFC in 2005.