TradeDoubler, which began its partnership programme with Opodo in 2002, will now be sole affiliate marketing provider for the portal, which specialises in flights, accommodation, car rental and travel details for holidaymakers.
The is owned by nine major European airlines, including British Airways, Air France, Lufthansa, KLM and Iberia.
Opodo said it chose TradeDoubler because of its proposals to "significantly ramp up" Opodo's online activity, and to commit to working with a long-term partner.
Paul Treanor, head of marketing at Opodo UK, said: "TradeDoubler is not merely an affiliate marketing company, they offer the strategic practices we need in order to grow our affiliate programme.
"We have an ambitious target to increase our growth over the next 12 months and we believe that TradeDoubler are positioned to help us reach those targets."