See main article: 2013 Citi Open. Alexandr Dolgopolov was the defending champion, but lost to Indian qualifier Somdev Devvarman in the second round.
Juan Martín del Potro won his third Citi Open title and second title of the year, defeating John Isner in the final, 3–6, 6–1, 6–2.
All seeds received a bye into the second round.