RP Motorsport driver Vitor Baptista claimed the championship title by five points (on dropped scores), winning six races during the 2015 campaign, including four consecutive victories during the second half of the season.
The runner-up position in the championship went to Konstantin Tereshchenko for Campos Racing, who like Baptista, took six victories during the season.
The championship top-three was completed by Yu Kanamaru, who took a single race victory at Silverstone for Emilio de Villota's team.
In the Spanish Formula Three sub-classification, Tereshchenko and Campos Racing snared their respective titles.
With Tereshchenko's four wins, Campos Racing finished nine points clear of RP Motorsport in the teams' championship.