The contract will include jack-up barges, supply ships, standby vessels and helicopters, as well as crews.
Walter Thain, senior vice president Europe for Petrofac offshore projects & operations, said: "With 45% of the world’s current consented offshore wind energy projects located in Germany, this is a growing target market for Petrofac.
"This contract demonstrates our ability to export our expertise in offshore oil and gas into new markets and new geographies. We believe we have much to offer the growing offshore wind market, and look forward to working with key players such as Siemens to support Germany’s ambitions for renewable energy."