The agency won the business after a two-way pitch against the Spanish incumbent, Senora Rushmore Madrid.
Mother will now create a campaign to run across all of Coca-Cola's European markets next summer, including the UK, France, Germany, Italy, Spain and Portugal.
The brief is to push the brand as the drink of the summer using the existing "Coke side of life" proposition.
The appointment strengthens Mother's relationship with Coca-Cola. It won the pan-European account for Diet Coke last month without a pitch and it handles a number of Coca-Cola brands in the UK, including Schweppes, Lilt, Oasis, Powerade and Dr Pepper.
Coca-Cola is changing its ad strategy from a market-by-market approach towards regional campaigns in a bid to bring greater consistency to its communications.
The company moved the pan-European ad brief for Sprite to Ogilvy & Mather Frankfurt in July.
Advertising for the main Coke brand has historically been handled on a market-by-market basis, but recent campaigns, including the "video game" spot from Wieden & Kennedy US and this summer's Euro 2008 "unhuggables" campaign by Santo, have run in multiple markets.