2009 Australian Open – Men's singles

Rafael Nadal defeated Roger Federer in the final, 7–5, 3–6, 7–6^(7–3), 3–6, 6–2 to win the men's singles tennis title at the 2009 Australian Open. It was his first Australian Open title and his sixth major title overall. Nadal became the first Spaniard to win the title. It was Nadal's third victory over Federer in a major final in eight months, following wins at the 2008 French Open and 2008 Wimbledon Championships.

Novak Djokovic was the defending champion, but retired due to heat stress in the quarterfinals against Andy Roddick.

The 2009 men's singles edition is considered to be one of the best majors in the Open Era. It is remembered for containing many of the best matches of the season, including the Nadal–Fernando Verdasco semifinal (lasting 5 hours and 14 minutes) and the final. It was also the first hard court major in which Nadal reached the final.