Livra runs a panel of 1m Spanish and Portuguese speaking consumers in Argentina, Brazil, Chile, Colombia, Costa Rica, Mexico, Portugal, Spain and Venezuela.
Gonzalo Santamarina, chief executive of Ipsos in Argentina, said: "There is no equivalent business to Livra in Latin America. They have very talented teams who understand how to build and engage panels and do research online.
"Thanks to this acquisition Ipsos reinforces its strong capabilities in Latin America, and improves its positioning in the growing online business."
Martin Anazco and Diego Meller founded Livra in 1999 and will continue to run the company independently of Ipsos.
Anazco said: "This is an exciting new opportunity for Livra. Ipsos understood our strategy and realized how our platform could ultimately be applied on a bigger scale.
"This partnership will help us push these innovations even further and provide huge benefits to our clients."
Livra, which currently has teams in Buenos Aires, London, Mexico City and Sao Paulo, has plans to expand into the US Hispanic market.
In February this year, TNS established a preferred partner relationship with Livra to access its online panels.