The 2015 GP3 Series was the sixth season of the third-tier of Formula One feeder championship and also sixth season under the moniker of GP3 Series, a motor racing feeder series that was run in support of the 2015 FIA Formula One World Championship and sister series GP2. Thirty-one drivers represented eight teams over the course of the season's nine rounds, starting in Spain on 9 May and ending in Abu Dhabi on 29 November. It was the final season for the Dallara GP3/13-AER P57 V6 chassis and engine package that debuted in 2013. A new Dallara-built chassis was introduced for 2016 along with a Mecachrome normally-aspirated V6 engine.

The GP3 Series, or GP3 for short, was a single-seater motor racing series launched in 2010 as a feeder series for the GP2 Series, introduced by GP2 organiser Bruno Michel. GP3 followed the entire European leg of the Formula One series and the GP2 series as a support race for the two. Like the GP2 series, GP3 gave drivers the experience of the Grand Prix environment, and took advantage of the infrastructure, such as marshals and medical facilities, in place for the Formula One events. GP3 Series mainly raced on European circuits, but had appearances on other international race tracks, with rounds in the 2015 season at the Bahrain International Circuit in Bahrain and the Yas Marina Circuit in United Arab Emirates.