Aegis is paying an initial consideration of €5.6m (£3.9m) plus a deferred cash consideration of up to €1.7m for the business. Columbus Quanti produced revenues of €6m last year.
Robert Lerwill, the chief executive of Aegis, said: "The acquisition of Columbus Quanti is consistent with our strategy of investing in the development of strong global networks.
"The acquisition means that Synovate is now the market research leader in Belgium and the deal brings with it some innovative research solutions that will be expanded throughout our network."
Columbus Quanti was founded in 1996 and employs 40 people from its headquarters in Ghent.
The deal comes as Aegis is thought to be preparing a bid for United Business Media's market research business NOP.
WPP Group and Taylor Nelson Sofres are also understood to be in the running for the business, which has a price tag of £250m.
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