The Polish business, which employs 77 people, reported revenue of £5m in the year to 31 March 2014.
Atkins chief executive officer Prof Dr Uwe Krueger said: "The sale of our Polish business is a further step forward in the implementation of our strategy to optimise our portfolio of businesses, and focus our investment in markets where the Group can deliver profitable growth."
The transaction is due to complete next month.
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