It involves the production of up to 600 different types of mailing pack on a daily basis for EDF's 5m strong UK customer base.
"This has been a significant win against very stiff opposition," said Nova's managing director Andy Fry (pictured). "I am over the moon."
Nova is in talks with several other blue-chip companies following its attendance at the Technology for Marketing exhibition.
"We've got two more major client wins in the pipeline," said Fry. "But I can't say anything more than that at present."
3.5m-turnover Nova embarked on a major expansion last April after relocating to a 7,300sqm facility in Burgess Hill, West Sussex.
"The new facility gives us the capacity to quadruple our turnover," said Fry.
EDF Energy is one of the UK's largest energy companies and employs 12,000 people across the country. It awarded six printing companies a suite of contracts worth around 5m from last November.
Key suppliers include etrinsic, DSI Group, Howard Hunt, Anton Group, Waddington & Ledger and The Lettershop Group.