Daniel Kosakowski (born February 21, 1992) is a retired professional American tennis player.

He played for the University of California, Los Angeles and was named Pacific-10 Conference 2011 Freshman Player of the Year.

[1] Kosakowski spent the first two years of his professional tennis career playing in tournaments based in California, reaching the final of the USA F25 event in September 2010, eventually losing to Chris Guccione in straight sets.

[3][4] In June 2012, Kosakowski travelled to Italy to play in his first professional tournament outside the United States, competing as a qualifier in the Città di Caltanissetta.

He then beat Brazilian Thiago Alves in straight sets, before shocking third seed Frederico Gil, 6–3, 6–4, to progress to the quarterfinals of the event where he lost to fellow qualifier Alejandro Gonzalez.