The singers visited projects working to empower youngsters in the African country, where an estimated six out of 10 girls are made to become wives and mothers in exchange for a 'bride price' paid to their family.
Most end up starting a family in their early teens, even though under-18s are five times more likely to die during child birth than women in their 20s.
After speaking to those being helped by Comic Relief and the UK government's Common Ground Initiative, Wiseman stated: "My wedding to Marvin is just around the corner, so talking to girls who had been forced to marry much older men when they were just 12 or 13 years old and having babies so young was really emotional for me.
"I can't imagine how frightening it must be to be just a child, being forced to marry and having no choice as to when you are going to start a family, but unfortunately that's the reality for so many girls across Africa."
White added: "My little sister is 12 and the thought of her leaving school to get married and have children really upsets me.
"Girls her age deserve to be protected from this and it was brilliant to see how these projects are helping girls to finish education, get a job and aspire to a better future."
The Common Ground Initiative works with members of the Africa Diaspora living in the UK with African heritage and strong links to the continent, who have set up organisations to change the lives of those in some of its poorest countries.