More than 820,000 unemployed people have found work under a five-year government scheme which ends next month, figures show.
The Work Programme, aimed at the long-term unemployed, has supported 824,000 people.
The Employment Related Service Association, which represents providers of government employment schemes, voiced concern about specialist support for disabled jobseekers after the Work Programme ends in April.
A reduction in funding means that while 300,000 disabled people were given support between 2012 and 2015, this will fall to 160,000 in the next three years, said the ERSA.
Chief executive Kirsty McHugh said: "Today's report underlines just how successful the Work Programme has been.
"With referrals ending next month we should reflect on the transformative impact of the Work Programme on individual lives, businesses and communities.
"Yet it is also deeply concerning that far fewer jobseekers will have access to this kind of specialist support moving forward.
"The size of the new Work and Health Programme means that only one in eight disabled people who want to work will have specialist help to do so.
"While the Work Programme has played an important role in helping to reduce long-term unemployment, challenges around productivity and skills remain. Rather than taking our foot off the gas we should continue investing in high-quality specialist employment support as we move into a new future."