Eighty-three women supported by an agency working with prostitutes last year were trafficked to Ireland, the organisation has claimed.
Ruhama, which began 25 years ago offering outreach services to street-based sex workers, said the number of people illegally brought here to work as prostitutes increased by 17% in 2013.
The charity said it has assisted 2,500 women from 60 countries since 1989. More than 300 were given direct support in the last year.
Ruhama, which supports the campaign to make the buying of sex illegal as was introduced in Northern Ireland last month, said the number of women accessing support in 2013 increased by 18%.
It also said 219 women were given specific care plans to help them.
And reflecting on work with prostitutes on the streets, Ruhama said 70 women were supported with services offered through its dedicated outreach van.
Sarah Benson, chief executive of Ruhama, said the charity's work had been remarkable over the last 25 years.
"I am also struck by the many changes which have taken place in the Irish sex trade, particularly how it has become increasingly organised by criminal gangs and adapted to the use of modern telecommunications to operate," she said.
"Yet, among all those changes, some things have not changed fundamentally - there is still the persistence of harm, exploitation and risk which has always and which continues to pervade the sex trade."
Ruhama said it has been campaigning for more than a decade for changes in law to tackle the demand for the buying of sex.
Ms Benson said she hoped Justice Minister Frances Fitzgerald will "bring in necessary legislative changes and free women from exploitation".
Ms Fitzgerald said: "We must take action to prevent human trafficking, to protect its victims and prosecute those who perpetrate this evil crime. To achieve these aims we must work internationally, in partnership across Government, with other state agencies and, importantly, with civil society organisations such as Ruhama."
With the introduction of new laws in Northern Ireland to criminalise the purchase of sex, a group of workers involved in prostitution protested at Stormont against the reform and issued a statement claiming it was a devastating move.
Some sex workers believe the criminalisation will drive the industry further underground, increase risks for marginalised prostitutes and do nothing to reduce trafficking.