The grant will go towards Dong’s £11.5 million proposal to set up a base to support the construction and operation of its 210MW Westermost Rough offshore wind farm in the North Sea.
The port at Grimsby is the closest to the North Sea wind farm and is already home to other operators, including Siemens, Centrica, E.on and RES Offshore.
The project off England's Yorkshire coast will be fully commissioned during the first half of 2015 and feature the first commercial deployment of Siemens' new 6MW offshore wind turbine.
Lord Haskins, chair of the Humber Local Enterprise Partnership, said: "The move further strengthens Grimsby’s position as a UK centre for operations and maintenance offshore support activity, which is playing a key part in the Humber's growth as the UK's energy estuary."