Numerous concerns have since been raised including that the large sum paid for the girl on social media could urge others to do the same, and there are calls for Facebook to take tougher action.
"That a girl could be sold for marriage on the world's biggest social networking site ... is beyond belief," said George Otim, country director of Plan International South Sudan told Reuters.
Facebook reportedly told the Thomson Reuters Foundation that after it was made aware of the material it did remove the post last Friday because it violated its community standards.
"Any form of human trafficking whether posts, pages, ads or groups that co-ordinate this activity are not allowed on Facebook," a spokesman said.
While child rights groups welcomed the action Facebook took, they noted that in taking several days to do so, it still ultimately resulted in the illegal marriage of a minor.
"Facebook has a responsibility on securing and protecting the rights of women and girls," Judy Gitau, a lawyer at Equality Now, told the Thomson Reuters Foundation.
"They need to put sufficient resources into monitoring what is on their platform."
According to the United Nations children's agency, UNICEF, more than 50 per cent of South Sudanese girls are married off before they turn 18, despite it being illegal to do so.
However many communities see marrying their child off early as the lesser or two evils, enabling them to collect resources in the form of a dowry and protect the girl from pre-marital sex.
