Amber Rudd (above) will tell the Santa Marta Conference in Rome that Britain will spend £11 million in high-risk countries from which victims are trafficked to the UK.
Santa Marta was launched by the Catholic Bishops' Conference for England and Wales and has the backing of Pope Francis.
The pontiff says the aim of the church group is to eliminate human trafficking and modern slavery.
Ms Rudd said: "Modern slavery is a global crime which demands an international response.
"Only by working together can we win the fight against this barbaric crime, which destroys the lives of the most vulnerable.
"Britain has taken world-leading action to tackle modern slavery. We are determined to work with other governments around the world to eradicate slavery and send a message that it will not be tolerated.
"As part of our ongoing commitment to tackle the scourge of modern slavery, these funds - totalling £14 million - will help develop innovative approaches to support victims and bring perpetrators to justice."
The investment comes from £33.5 million in overseas aid funding to support the fight against modern slavery which was announced in July.
Last week, Ms Rudd announced that police are to receive an £8.5 million cash injection to bolster efforts on the issue.
Earlier this month, the UK's anti-slavery commissioner warned that victims were being failed by "substandard" crime recording.
