Theresa May expressed her support for the three-year Clewer Initiative ahead of a launch at Lambeth Palace, saying it was important to "shine a light on this hidden crime".
Mrs May added: "Tackling modern slavery is one of my priorities as Prime Minister, and as Home Secretary I was pleased to introduce the Modern Slavery Act 2015, giving law enforcement new tools to pursue criminals and increase the support available for victims.
"However, the Government cannot tackle this problem alone and this is why the efforts of organisations and groups such as the Clewer Initiative are so important."
Incidents of people being forced to work against their will under the threat of punishment, human trafficking, child slavery, and forced or early marriage are all considered forms of modern slavery, according to the Anti-Slavery International.
The Church of England hopes all its 12,000 parishes will eventually participate in the programme which aims to support victims of modern slavery and identify where it is happening.
Ten dioceses - Bath and Wells, Chester, Derby, Durham, Guildford, Lichfield, Liverpool, Portsmouth, Rochester, and Southwell and Nottingham - have already signed up. Fourteen more are due to take part later this year.
Independent Anti-Slavery Commissioner Kevin Hyland said: "Faith groups have influence, insight and rare avenues into the community. They are therefore a powerful tool in the fight against modern slavery."
The Clewer Initiative is being funded by the Clewer Sister, an Anglican order of Augustinian nuns which was founded in 1852 to help marginalised younger women.
Click here to listen to Bishop Bishop of Derby, Rt Rev Alistair Redfern, the Church of England's lead on modern slavery, speaking with Premier's Alex Williams: