Formula Renault 3.5 occupied a position alongside GP2 as one of the two premier Formula One feeder series, attracting a mix of drivers progressing from British Formula Three, the Formula Three Euroseries, and GP2. The season began on 18 April at the Circuit de Catalunya and concluded on 25 October at the newly opened Ciudad del Motor de Aragón circuit in Alcañiz, adding a significant new venue to the calendar for the series finale.
Several technical and sporting regulation modifications were introduced for 2009. On the technical side, the aerodynamics of the existing Dallara chassis received minor enhancements inspired by developments in the 2009 Formula One regulations. Sporting changes focused on cost reduction and the showcasing of driver talent. Thursday test sessions at each race weekend were replaced by two one-hour free practice sessions on Friday. Race duration was extended to 44 minutes plus one lap.
A notable addition was a bonus point awarded to the driver who gained the most places during each race, rewarding overtaking and encouraging aggressive strategy. The mid-season championship leader was also given the opportunity to demonstrate a Renault R28 Formula One car at a World Series meeting. After seven races, Marcos Martínez and Baguette were level on points; Martínez received the demonstration prize by virtue of his three race wins at that stage, and drove the R28 at the following Silverstone round. Baguette won the title at the Nürburgring, earning a season-end test with the ING Renault Formula One team.
KTR had been allocated entries for the season but withdrew on 1 April 2009 after team principal Kurt Mollekens announced he could not secure a driver line-up. Their slots were subsequently taken up by KMP Group/SG Formula, who announced their entry on 14 May 2009.
The grid featured an exceptionally strong crop of drivers. Daniel Ricciardo arrived from British Formula Three with Carlin Motorsport, as did Jaime Alguersuari and Oliver Turvey. Jules Bianchi graduated from the Formula Three Euroseries, where he had raced with ART Grand Prix, and joined KMP Group/SG Formula. Brendon Hartley entered with Tech 1 Racing after British Formula Three, as did Edoardo Mortara, who split time between KMP Group and Tech 1 Racing having come from the GP2 Series. Stefano Coletti joined Prema Powerteam, having also graduated from European Formula Three.
Dani Clos moved across from GP2 to Epsilon Euskadi. Salvador Durán arrived from A1 Grand Prix competition. Adrián Vallés returned from GP2 to join Epsilon Euskadi. Several drivers entering from the International Formula Master also joined the field.
The championship was competitive through the first half of the season, with multiple drivers including Marcos Martínez contesting the lead. After the halfway point, Baguette's consistency and pace in the second half of the year allowed him to pull away from the rest of the field and wrap up the title before the final round at Aragón.
The teams' championship was won by International DracoRacing, with Carlin Motorsport finishing as runners-up.
The 2009 Formula Renault 3.5 grid included several drivers who went on to Formula One careers. Daniel Ricciardo debuted with HRT in 2011 and subsequently raced for Toro Rosso, Red Bull, Renault, McLaren, and AlphaTauri. Jaime Alguersuari raced for Toro Rosso between 2009 and 2011. Jules Bianchi progressed to Marussia in Formula One in 2013, tragically suffering fatal injuries after a crash at the 2014 Japanese Grand Prix. Bertrand Baguette himself earned a Formula One test with Renault at the end of the season as part of his championship prize.
Points for both the drivers' and teams' championships were awarded as follows across each race: a standard points scale for finishing positions, plus one bonus point for the driver who gained the most places during the race. The maximum points a driver could score in a single non-Monaco, non-Portimão weekend was 32, and a team could earn a maximum of 57. At Monaco and Portimão, qualifying points were awarded by group rather than through a Super Pole session.