Most of the 14% rise in pre-tax profits to £8.8m came from the engineering services business, which works on the Sellafield clean-up and the Magnox programme.
Revenue rose 5% to £265m with engineering services delivering 85% of group sales.
Roy Harrison , chairman, said: “It remains the board’s strategy to grow our engineering services business, both organically and through selective earnings enhancing acquisitions.”
Harrison said that Renew was on track to achieve its target of a 4.5% group operating margin for the year ending 30 September 2017.
The firm’s specialist London building business delivered an operating profit of £1.1m (2015: £1.0m) on stable revenue of £44m.