"The repayment has contributed to the reduction of Unicorn's liabilities from over US$600 million in 2009 to minimal levels currently," Ikbal Daredia, acting chief executive, said.
Investment banking in Bahrain has been hard hit by a regional property crash in 2008.
Unicorn's business is slightly more diversified than other Bahraini investment houses.
Last August, Unicorn's top executive left after a dispute with its board over strategy, sources told Reuters.
Majid Al-Refai advocated making the investment bank a global Islamic finance player but the board demanded more focus on Saudi Arabia.