Chalke, who will advise the UN on Community Action against Human Trafficking within the UN's Office on Drugs and Crime (UNODC), addressed the opening session of the UN GIFT conference in Vienna last week.
"My appointment is simply a symbol of the power for change that 1.5 million voices have created," said Chalke.
"The crime of people trafficking or, to put it in stark terms, modern slavery, for sex, forced labour and even organ harvesting is one that shames us all.
"However, though the reality is that trafficking is now the world's fastest growing crime, I believe that every person, corporation and government can make choices which will turn the tide and that together we can see this great evil defeated. Stop the Traffik remains absolutely committed to that goal."
During the session, the Stop the Traffik coalition of 1,000 organisations engaged in anti-trafficking work also presented its Global Declaration signed by more than 1.5 million people.
The 1,200-strong delegation of leaders drawn from all 192 UN member states was joined by actress and activist Emma Thompson, Latin American star Ricky Martin, who is now involved in anti-trafficking work in both North and South America, and the Executive Director of the UNODC, Antonio Maria Costa.
Chalke's appointment is part of a wider collaboration between the Stop the Traffik coalition and the UNODC that will see the two bodies working together to produce resources for and strengthen connections with grassroots communities around the world. The organisations will also undertake joint research into trafficking in goods and product supply chains.
Speaking from Vienna for the United Nations, Costa expressed his enthusiasm for Chalke's new role and the work of Stop The Traffik, adding: "I believe that the Stop the Traffik Coalition has the potential to provide significant impetus to the United Nations Global Initiative to Fight Human Trafficking."