The joint venture, with the Australasian engineering and property services company United Group, will build a new power line link from Whakamaru to Auckland.
The link between Whakamaru and Auckland will require the design, supply and construction of a 400kV-capable overhead line of around 186km in length.
Construction is scheduled to begin in 2009 and the line is expected to be commissioned in November 2011.
Balfour Beatty chief executive Ian Tyler said: “We are delighted to have been selected by Transpower to construct the proposed transmission line from Whakamaru to Auckland, which will help provide security of supply to the upper North Island.
“We look forward to deploying our expertise and resources, working in joint venture with United Group Limited, to deliver this important project.”