 Koroma joined the Sierra Leone National Insurance Company in 1978.In 1985, he joined the Reliance Insurance Trust Corporation (Ritcorp), and in 1988, he became managing director of Ritcorp, remaining in that position for 14 years.A longtime member of the Wesleyan Church of Sierra Leone, Koroma married Sia Nyama Koroma, the daughter of attorney and politician Abu Aiah Koroma.