The group agreed a 35p offer from Canadian group WSP last month valuing the group at £24mln.
Net losses for the year to March were £19.5mln after hefty charges related to restructuring, legal action and disposals as chief executive Douglas McCormick cleaned up the business.
McCormick, who joined last year, said the group had delivered on all its strategic objectives during the year.
“We have sold the APAC and India businesses; announced our exit from MENA; concluded the legacy SFO issues; and restructured the Group to operate across five separate regions.”
Joining WSP will provide Sweett with a stronger platform both operationally and financially for growth in the years ahead, he added.
Sweet was fined £2.25mln in February related to bribery offences that took place in the UAE in 2010.