M2 Subsea - headquartered in Westhill - will tackle explosive devices lying at the bottom of the Baltic Sea since World War 2.
Two remotely-operated vehicles (ROVs) will work from the Go Electra support vessel.
The contract was awarded by Next Geosolutions.
M2 Subsea chief executive officer Mike Arnold said: "This contract award from Next Geosolutions is great for the business and a significant scope of work for us to win.
"It highlights both our capabilities to negotiate what is a very challenging subsea environment.
"Safety is a key factor on every project and in particular where it involves surveying the seabed to identify undiscovered explosive devices for removal."

Government figures show the resort has the most pregnant smokers per head of population.
Blackpool Council said smoking levels in the town had fallen from 33% five years ago to 27.2% now.
In 2013, it won an award for its work tackling the issue of smoking by expectant mothers.
Current NHS data shows the rate of smoking throughout pregnancy in Blackpool was more than 10 times that in Westminster (2.1%).
Blackpool Councillor Eddie Collett, the Cabinet member for health and wellbeing, said: "In Blackpool, smoking in pregnancy numbers are falling. We have seen significant improvement since 2010."
He said they needed to continue the positive work to ensure mothers and babies were protected from harm caused by smoking.
"There is still a way to go," he added. "However, I am pleased that we are moving in the right direction."
He said there were close links between maternity services and support services.
Two years ago Blackpool received an award on smoking cessation from the Clear Partnership, which works with local authorities and is supported by charities such as Action on Smoking and Health (Ash).
Hazel Cheeseman, director of policy at Ash, said the data came from the government's Smoking at the Time of Delivery data.
She said it was unfair to single out Blackpool as they have done some "great work" and one of the reasons the figures may seem higher is because they are so good at recording the data and "not every other part of the country is quite as scrupulous."
She added there are lower rates of smoking in more affluent areas and higher in areas that are less affluent, and although Blackpool has invested a lot they "have such a mountain to climb,"
At the time of the award, Cancer Research UK's Tobacco Control lead, Alison Cox, said: "Blackpool's excellent work will ensure that more pregnant women get the help they need."
An Aberdeenshire subsea business has won a contract worth more than £1m to remove explosives from around the world's longest pipeline.
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A councillor in Blackpool, which has England's highest smoking rate among pregnant women, has defended the town's record.