Vauxhall was awarded the Fleet Manufacturer of the Year award by a panel of industry experts at the ceremony in the Grosvenor House Hotel.
Judges praised the manufacturer for the large dealer network, customer service and green credentials.
Fleet News editor Stephen Briers said: "Vauxhall’s extensive dealer network, the innovative way it maintains its market position and its strong fleet model line up, which includes the ecoFLEX green range, were behind our readers’ decision to vote Vauxhall as their fleet manufacturer of the year."
The first ever Best Technical Innovation Award was won by Ford for advances in safety, emissions reduction and convenience in the fleet.
It was a double celebration for Ford, as the S-Max picked up the Best MPV award, beating competition from the Mazda6 and Renault Grand Scenic.
However, Ford was beaten by BMW to the Green Manufacturer of the Year Award. The final manufacturer award, the Most Improved Manufacturer, was awarded to Skoda.
In the car awards, the Mazda6 won Best Estate on a night dominated by Volkswagen. The Golf won Company Car of the Year and the lower medium award, while the Polo took home the Best Supermini title.
Jaguar won the Executive category with the stylish XF, and BMW was awarded the Best Luxury car for the 7-Series.
The Fleet News Awards also recognised the best fleet suppliers and individual fleet managers in the annual ceremony.