The acquisition will enable Retail Eyes to focus on both sustaining growth in the UK and develop the business in European markets.
Its Milton Keynes office will become the Market Force European headquarters.
Both companies offer customer intelligence solutions from mystery shopping to customer satisfaction and in-store auditing.
Retail Eyes chief executive Tim Ogle said: “I am delighted that our business will become a part of Market Force. It will be the springboard for even more growth for us. We have achieved fantastic results since we launched in 2003.
“Market Force’s experience and support will give us the financial and experiential resources needed to grow the business further, both here in the UK as well as throughout Europe.”
The acquisition of Retail Eyes adds more than 100 world-class clients to Market Force’s portfolio and will double the number of mystery shoppers and retail auditors in the company’s network to more 600,000 across Europe and the Americas.
The expected revenue of the expanded company is set to exceed more than £45 million in 2011.
Market Force chief executive Karl Maier said: “There is no question that Retail Eyes has the most sophisticated customer intelligence business in the UK, with a rapidly growing European practice.
"This acquisition will enable us to serve our multi-national clients, as well as extend our services to new markets that have huge potential for growth.”