2019 US Open – Boys' singles

Jonáš Forejtek won the boys' singles tennis title at the 2019 US Open, defeating Emilio Nava 6–7(4–7), 6–0, 6–2 in the final.

Thiago Seyboth Wild was the defending champion, but he is no longer eligible to participate in junior events.

Seeds
• 🇯🇵 Shintaro Mochizuki (second round)

• Holger Vitus Nødskov Rune (second round)

• 🇺🇸 Martin Damm (second round)

• 🇨🇿 Jonáš Forejtek (champion)

• 🇦🇷 Thiago Agustín Tirante (second round, retired)

• 🇺🇸 Toby Kodat (second round)

• 🇫🇷 Harold Mayot (second round)

• 🇺🇸 Emilio Nava (final)

• 🇧🇪 Gauthier Onclin (third round)

• 🇨🇦 Liam Draxl (third round)

• 🇺🇸 Brandon Nakashima (semifinals)

• 🇯🇵 Shunsuke Mitsui (first round)

• 🇯🇵 Keisuke Saitoh (first round)

• 🇫🇷 Valentin Royer (quarterfinals)

• 🇨🇿 Jiří Lehečka (quarterfinals)

• 🇭🇺 Péter Makk (third round)

Seeds
• # Kārlis Ozoliņš (qualified)

• # 🇬🇧 Harry Wendelken (first round)

• # 🇨🇿 Andrew Paulson (qualified)

• # 🇦🇷 Román Andrés Burruchaga (Qualifying competition)

• # 🇯🇵 Ryuhei Azuma (qualifying competition)

• # 🇫🇷 Timo Legout (first round)

• # 🇯🇵 Taiyo Yamanaka (qualifying competition)

• # 🇬🇧 Blu Baker (qualifying competition)

• # Arthur Craig Pantino (first round)

• # 🇮🇹 Lorenzo Rottoli (qualifying competition)

• # 🇧🇷 Natan Rodrigues (qualified)

• # 🇦🇺 Chen Dong (qualifying competition)

• # 🇫🇷 Baptiste Anselmo (first round)

• # Lodewijk Weststrate (first round)

• # 🇦🇺 Stefan Storch (qualifying competition)

• # 🇫🇷 Giovanni Mpetshi Perricard (qualified)

Qualifiers
• # Kārlis Ozoliņš

• # 🇺🇸 Aidan Mayo

• # 🇨🇿 Andrew Paulson

• # 🇺🇸 Cash Hanzlik

• # 🇫🇷 Giovanni Mpetshi Perricard

• # 🇧🇷 Natan Rodrigues

• # 🇩🇪 Milan Welte

• # 🇺🇸 Blaise Bicknell