United hopes the young Brazilian can add to a strike force which struggled to score goals in 2012.
Rafael Teixeira de Souza, 20, joins the Black-and-Red from Bahia of the Brazilian Serie A, where he has made 36 first-team appearances and scored 10 goals.
“We are very excited to have reached a deal to bring Rafael to D.C. United on a one-year loan with a view to a permanent transfer,” said D.C. United general manager Dave Kasper.
“He is a young, talented player with solid experience with the Brazilian Serie A club Bahia. We believe Rafael has all the qualities to be a successful striker in Major League Soccer, and we look forward to having him join us in preseason 2013,” Kasper added.
Rafael is now the youngest current Designated Player in the league, and the second-youngest Designated Player to sign in MLS history (Fabian Castillo was 18 when he signed with FC Dallas).
The Brazilian's loan deal includes an option in December that D.C. United can use for a permanent transfer.