Inform provides services such as IT channel sales tracking and reseller database products to IT vendors, distributors, resellers and retailers.
The acquisition will see GfK pickup Inform's 16 Sydney-based staff.
Inform managers will be retained including the former owners David Hancock, Terry Wiley and Chris Herbert.
Hancock has been appointing marketing director for the GfK Australia group of companies and will sit on the local board of directors, a statement said.
Wiley becomes new business services director and Herbert has been appointed director of the company's IT services division.
GfK claimed it's the number five research company worldwide and in Australia operates retail market measurements covering over 200 products sectors in the consumer durables and entertainment markets in Australia and New Zealand.
Its sell in division, Informark monitors supplier's deliveries to trade for 27 different industries. The company now employs 63 full time staff in Sydney and Canberra following the acquisition.