Samuel Sam-Sumana's dismissal comes almost two weeks after he was expelled from the governing All People's Congress (APC) and went into hiding, claiming he was in danger and asking the United States to grant him asylum.
"I have taken note of the decision of the APC," Koroma said in a statement read out intermittently on state radio overnight Tuesday to Wednesday.
"The public will recall, and I have also taken note of the fact that... Alhaji Samuel Sam-Sumana sought asylum from a foreign embassy, demonstrating a willingness to abandon his duties and office as vice president of our beloved republic."
The president said he was in talks with his party to "shortly" find a replacement for Sam-Sumana, his running mate in his successful 2007 and 2012 presidential campaigns.
The APC announced on March 6 it had kicked out Sam-Sumana for fomenting violence in his home district of Kono, deceit, fraud and threatening key party officials.
He was accused of lying about being a Muslim, inventing a university degree from the US, attempting to start up a breakaway party and keeping "over 100 groups of thugs to unleash violence against party people in the Kono district".
He denied all charges and fled into hiding, claiming he feared for his life and applying to the US Embassy in Freetown for asylum, according to his aides.
The government has repeatedly dismissed claims that the vice president is in any danger, claiming his fears for his life were "ludicrous".
The 52-year-old's expulsion came a few days after he had put himself in quarantine due to the death of one of his bodyguards from Ebola.
But religious leaders have warned that the "strained relationship" between the Sam-Sumana and Koroma threatened the stability of a country still recovering from its ruinous 1991-2002 civil war.
