The car manufacturer has appointed AKQA to handle its web design and build account following an extensive eight-week review of its digital agency arrangements.
AKQA secured the business following a competitive pitch against a shortlist of five agencies, thought to include Dare Digital and incumbent Arc Worldwide.
Fiat plans to revamp its websites across Europe next year in response to recent efforts by Volkswagen and Honda to strengthen their digital presence.
The Italian marque intends to increase its focus on online advertising and emerging channels.
Fiat and AKQA declined to comment on plans for 2007, but it is understood that the motor company will give the web a key role in promoting the launch of its latest Cinquecento and Grande Punto models.
The activity will see AKQA work closely with Fiat's ad agency, Krow, which secured the £3.5m UK account earlier this year after the car company parted ways with Leo Burnett.
In the past, Fiat has relied heavily on the web for launches and lead acquisition. It recently became the first automotive company to run a competition using Google Earth.
Fiat spent £320,000 of its £19.2m UK media budget on online advertising in the year to 31 October, according to Nielsen Media Research. This is expected to increase significantly during 2007.
Fiat sold 35,828 cars in the UK in 2005, giving it a market share of 1.47%, down on its 72,825 sales and 2.84% share in 2004, according to the Society of Motor Manufacturers and Traders.