2009 US Open – Boys' singles

Grigor Dimitrov was the defending champion, but did not compete in the Juniors this year.

Bernard Tomic won in the final 6–1, 6–3 against Chase Buchanan.

Seeds
• # 🇮🇳 Yuki Bhambri (quarterfinals)

• # 🇸🇪 Daniel Berta (first round)

• # 🇦🇺 Bernard Tomic (champion)

• # Huang Liang-chi (first round)

• # 🇦🇷 Agustín Velotti (first round)

• # 🇰🇷 Lim Young-kyu (second round)

• # 🇦🇷 Andrea Collarini (third round)

• # 🇫🇷 Gianni Mina (semifinals)

• # 🇯🇵 Shuichi Sekiguchi (first round)

• # 🇦🇷 Facundo Argüello (first round)

• # 🇩🇪 Kevin Krawietz (first round)

• # 🇫🇷 Julien Obry (second round)

• # Julen Urigüen (first round)

• # 🇻🇪 David Souto (first round)

• # 🇩🇪 Dominik Schulz (second round)

• # 🇺🇸 Denis Kudla (quarterfinals)