[3] Robles became the Nationals' top prospect after the team traded pitcher Lucas Giolito to the Chicago White Sox on December 7, 2016.

[9][10] Writer Jim Callis said that same month that he believed Robles could be considered the top overall prospect in baseball by the end of the 2017 season.

[13] On July 24, after 77 games with Potomac, batting .289 with seven home runs, 33 RBI, and 16 stolen bases, the Nationals promoted Robles to the Harrisburg Senators of the Double-A Eastern League.

On September 10, Robles reached base safely for the first time in his major-league career after being hit by a pitch.

Later in the game, he got his first career major-league hit, a double off the Nationals Park scoreboard, also getting his first RBI in the majors.

[17] He finished the regular season with the Nationals having played in 13 games, batting .250 with a double and two triples and driving in four runs.

[19] After Washington lost the 2017 NLDS to the Chicago Cubs in five games, Robles played in the Arizona Fall League.

[23] Robles hit .188 in 21 spring-training games in 2018 before the Nationals optioned him to the Syracuse Chiefs of the Triple–A International League.

[24] Robles started a rehab assignment with the Gulf Coast League Nationals on July 7, alongside fellow Chiefs outfielder Alejandro De Aza.

[19] In 2019, Robles batted .255/.326/.419 with 17 home runs, 65 RBI, 25 hit by pitch (2nd in the NL), and 28 stolen bases (5th) in 37 attempts.

[29] He led all center fielders with 12 assists but also tied for the National League lead with 6 outfield errors.

[33] Robles started all seven games of the World Series, hitting just .160 in the bottom third of the batting order, as the Nationals defeated the Houston Astros to win their first championship.

[48] Robles had one of the most productive stretches of his big league career with the Mariners in 2024,[49] batting .328 with 4 home runs and 30 stolen bases in 77 games.

[19] He became the team's leadoff hitter by the end of July and played all three outfield positions, often filling in for Julio Rodríguez in center field.

Robles briefly laughed with Gil before the injury forced him out of the game, a blowout loss to the New York Yankees.