The large-format company will produce decorations, information boards and acrylic materials, such as £10,000 worth of signage, for each of the company's call centres, as well as £200,000 worth of work for the head office in Sunderland.
The job involves the printing of npower's new red-and-blue logo and other branding, which was designed by Leeds-based WPA Pinfold.
A six-colour Roland roll-fed solvent printer and an Océ Arizona 350 GT fltabed produced most of the work for the 12-month project, which is due to be completed in December.
Chris Stringwell, director and cofounder of Digital Plus, said npower was sponsoring all 72 football league clubs and that the pitch in Sheffield was for "staff kick-arounds".
Projects director John Webster said: "This is a great contract for the team and working with WPA Pinfold has created a strong partnership."