Semco said it is the company's largest ever order for telecoms equipment in the offshore wind sector.
The Danish firm will deliver its products to four of Dong's UK projects; Burbo Bank Extension and Race Bank in 2015; the Walney Extension by end of 2015; and Hornsea 1 in 2016/2017.
The order includes the design, testing, shipping, installation and commissioning of the digital telecoms equipment.
Semco's package will also include technology, allowing engineers to communicate from within the turbine tower. According to Semco, a turbine tower "acts as a faraday cage" interfering with reception. It said its system has nullified this issue.
Semco Maritime senior vice president Henrik Lunde said the contract was a "good opportunity" for the group. He added Semco would be carrying out "cost-cutting exercises" in this deal.
Previously, Semco has provided telecommunications to phase one of the London Array project.