The 2009 Gerry Weber Open was a men's tennis tournament played on outdoor grass courts. It was the 17th edition of the event known that year as the Gerry Weber Open, and was part of the ATP World Tour 250 series of the 2009 ATP World Tour. It took place at the Gerry Weber Stadion in Halle, North Rhine-Westphalia, Germany, from June 6 through June 14, 2009.

The singles draw featured Miami, Monte Carlo and Rome finalist, Dubai and Belgrade titlist Novak Djokovic and 2008 Davis Cup winner, Brisbane runner-up Fernando Verdasco. Also seeded were Johannesburg and Marseille winner Jo-Wilfried Tsonga, Munich champion Tomáš Berdych, Dmitry Tursunov, Jürgen Melzer and Rainer Schüttler. Association of Tennis Professionals (ATP) No. 2 Roger Federer, reigning US Open champion, winner of the Madrid Open and runner-up in the 2009 Australian Open, was initially in the draw as the top seed, but pulled out before playing a match, citing fatigue after winning the French Open the previous week.