The Nationals selected Pineda's contract from Triple-A Rochester on Friday.
Pineda began the season playing in High-A and quickly ascended through the Nationals' farm system. Now, the 22-year-old backstop will play in the majors for the first time in his young career. He will almost certainly be used as a depth piece behind the dish for as long as Keibert Ruiz (groin) remains on the injured list