The Wiltshire-based organisation announced it had joined forces with Interwork, a specialist disability employment organisation based in Adelaide, south Australia, with an annual turnover of £5m.
Bernie Jones, international director at the Shaw Trust, said the move would enable it to enter the Australian welfare-to-work market and share experience and best practice.
"This merger will help strengthen the third sector's position as a prime provider of welfare-to-work programmes on an international scale," he said.
Charlesworth and chief finance officer Julie Currin, who had also voiced concerns about plans to expand into Australia, left the Shaw Trust in quick succession last year.
Shortly afterwards the charity, which is the largest voluntary sector provider of employment services for disabled people, announced it had put its overseas expansion plans on hold because of the economic downturn.
Jones said the merger presented different opportunities from the ones that were considered last year. "We don't believe it is a risky venture," he said.
"The board and the senior management team at the Shaw Trust have always been interested in entering the Australian welfare-to-work market, and Interwork has provided us with a great chance of doing this."
He said the two organisations had started merger talks this year but informal contact had existed for some years. The organisation will continue to use its existing names in the respective countries.
Last month the trust blamed the start-up costs of welfare-to-work programmes in the UK for its £2.8m loss in 2008/09.