Washington also agreed to a deal with 16-year-old Dominican infielder Luis Aquino, who is the nephew of former Nationals shortstop Cristian Guzman.
In accordance with the Collective Bargaining Agreement, each team is allotted a $700,000 base and a bonus pool with four slot values based on the team's record in 2014 for the international signing period, which started Thursday. Washington's overall pool total for this year's signing period is $1,985,400.
Considered "a gamer" in the scouting community, Soto has above-average offensive tools and a graceful swing. He is not known to have a ton of raw power, but he doesn't swing and miss often. Scouts also rave about his knack for barreling balls.
On defense, Soto has an average arm and good instincts. He would be in the competition for the overall top player in the class, but he is held back a bit by his running ability.
"Soto is a left-handed hitter with advanced feel for hitting and projection for power," said Nationals director of Latin American operations, Johnny DiPuglia. "He profiles as a corner outfielder with a solid arm and good instincts."
Aquino is a switch-hitter, who the Nationals believe can play both middle-infield positions.
"Aquino is a speedy, athletic middle infielder with the skills to hit at the top of the order," DiPuglia said.
Jesse Sanchez is a national reporter for MLB.com. Follow him on Twitter @JesseSanchezMLB. This story was not subject to the approval of Major League Baseball or its clubs.