TRG Wind will start work in Germany this month on a retrofit programme covering more than 560 wind turbines.
The contract is expected to last a year and, added to an expanding international workload, strengthens the company's foothold and future.
Recruitment as a result of the growth has taken TRG's workforce to almost 50 and the company has also bought 16 new vans and pick-up trucks, which will service the contracts from the operational centre in Hull.
David Elcombe, managing director of TRG Wind, said: "The contract in Germany is with one of the biggest and fastest-growing wind turbine manufacturers in the world and winning it is a significant achievement.
"Germany is the biggest wind energy market after China and the US and the maturity of the sector there is reflected throughout the supply chain.
"There is a very big industry growing up around it and we have managed to prove ourselves against strong competition in terms of quality, planning and efficiency.
"There is an end date to the new contract, but we are looking beyond that because, in addition to being a business win, it is an opportunity.
"It gives us a foothold in a very exciting market and it further strengthens our reputation in the UK and internationally."
TRG Wind was formed in London in 2014 by individuals who brought together experience in onshore and offshore wind in partnership with specialists from the finance and recruitment sectors.
The company provides supervision, inspection and installation services to wind turbine manufacturers and operators to ensure the highest standards of quality and safety in constructing, commissioning and maintaining turbines.
TRG Wind utilised the support of the Green Port Growth Programme’s Inward Investment team to identify a base in Hull and received funding to help move operations to the city last year. The company is now operating in 20 countries, with engineers currently working in conditions as varied as the summer heat of South Africa and the plummeting recent temperatures of Romania and Greece.
Turnover reached £1.5m during TRG's first year, and the company expects to report growth of 150 per cent for last year with continuing success to follow.
Mr Elcombe said: "The move to Hull has been a big success and we have already secured enough business to achieve 100 per cent growth during 2017.
"The port gives us easy access to the rest of Europe and there are a lot of people in the area who have the background and the skills that we are looking for.
"Our recruitment since opening the Hull depot has been gradual, but, from starting out with a handful of people, we are now close to 50 and there will be more on the way.
"We have worked in the onshore wind industry for many years and we are adding to that and increasing our offshore work.
"We know what the big manufacturers need and we train our people to meet those specific requirements."