The New York-based bank will also be selling off its trademark red umbrella to The St Paul's Travelers Companies for an undisclosed fee.
In a statement, Citigroup said that, from the beginning of the second quarter of this year, businesses to begin using the new name and branding include Citi Smith Barney wealth management, Citi Investment Research, Citi Private Bank and Citi Alternative Investments.
Commenting on the initiative, the bank's chief executive Charles Prince, said that Citi "is how most of our clients think about us already".
"Through a unified brand, we will leverage this symbol," he added.
However, it was confirmed that, while the bank will operate as Citi, its legal name will remain Citigroup Inc.
The bank follows the lead of the US firms Apple Inc and the disability insurer UnumProvident Corp, both of which have announced name changes this year.