Catholic missionaries were active in the coastal regions of Sierra Leone from the early sixteenth century although only a few people converted to Catholicism.

[4] The vicariate was elevated to the status of a diocese, taking the name of Freetown and Bo on 18 April 1950.

It was established on 11 November 1970, with its territory being split off from the diocese of Freetown and Bo.

[6] In January 2011, the Diocese of Bo (Dioecesis Boënsis) was created in 2011 by Pope Benedict XVI[7] through the bull Petrini ministerii.

The seat of the diocese is at the Immaculate Church of Mary where the Roman Rite is observed and serves as the seat of the Diocese of Bo (Dioecesis Boënsis) which was created in 2011 by Pope Benedict XVI[7] through the bull Petrini ministerii.