Banda made his major league debut on July 22, 2017, taking the loss in a game against the Washington Nationals. Banda was effective for the first two times through the division-leading Nationals' batting order, giving up his only run on a titanic solo shot by Bryce Harper that reached the Chase Field concourse but gave up three more runs and was pulled in the sixth inning. He was optioned back to Reno the next day. He was recalled twice more and finished the season with a 2–3 record and 5.96 ERA in innings. In 22 starts (10th-most in the league) for Reno he was 8–7 with 12 wild pitches (2nd), 116 strikeouts (5th), 51 walks (7th) and a 5.39 ERA.
