2021 US Open – Boys' singles

Boys' singles
2021 US Open
Champion Daniel Rincón
Runner-up Shang Juncheng
Score6–2, 7–6(8–6)

Jonáš Forejtek was the defending champion, having won the previous edition in 2019, but was no longer eligible to participate in junior events.

Daniel Rincón won the title, defeating Shang Juncheng in the final, 6–2, 7–6(8–6).