GroupM is has created a dedicated MEC-backed unit called Primus to house the account.
Primus will handle the UK, France, Germany, Russia, Central and Eastern Europe.
Carat had held the EMEA account since 2007.
In a statement J&J told Media Week: "The outcome of the comprehensive review is that we are consolidating our media planning and buying agencies for our consumer businesses and brands in EMEA from four to two.
"MEC and Universal McCann will begin their new contract with us, effective, January 1, 2013. We will work closely with our agency partners over the next few months to ensure our brands have optimal support during the transition period."
According to Nielsen figures, J&J spends £19 million on UK media. Brands supported include Listerine and Neutrogena.
UM will handle the J&J media account Spain, Italy, Portugal, the Middle East, North Africa, Pakistan and the Balkans.