Tennis at the 2011 SEA Games – Men's singles

Cecil Mamiit is the defending champion of the Men's Singles competition of the 2011 SEA Games but lost in the semifinals to Christopher Rungkat. Rungkat won the title by beating top seed Danai Udomchoke 6–2, 6–2 in the final.

Seeds
The top seed received bye to the quarterfinals. • # 🇹🇭 Danai Udomchoke (final)

• # Christopher Rungkat (champion)

• # 🇹🇭 Kittiphong Wachiramanowong (quarterfinals)

• # Elbert Sie (semifinals)