The Nationals selected Noll in the seventh round of the 2016 Major League Baseball draft, making him the fifth-highest draft pick in Florida Gulf Coast history and the second-highest among position players. Many prognosticators had expected him to be drafted a round or two higher. Noll chose to sign with the Nationals and was named among the organization's Minor League Baseball All-Stars at the end of the 2016 season, progressing from the Class A Short SeasonAuburn Doubledays up to the Class A Full SeasonHagerstown Suns over the course of his campaign. Noll continued his development in 2017, ending the year with the Class A-AdvancedPotomac Nationals. Noll was one of six Potomac Nationals honored as Carolina League All-Stars in 2018. He played for the Salt River Rafters in the Arizona Fall League following the 2018 season. Primarily a second baseman in 2016 and 2017, Noll played mostly corner infield positions in 2018. After the 2018 season, MLB Pipeline ranked him as the Nationals' 31st-best prospect; in April 2019, he moved to 27th on the list. Noll received a non-roster invitation to major league spring training in the 2019 preseason. A strong spring performance saw him stand alone as the last non-roster player in major league camp by the final day of spring action in Florida. After fellow infielder Adrián Sánchez was optioned to the Class-AAA Fresno Grizzlies following the final spring training game, the Nationals selected Noll's contract and promoted him to the roster for Opening Day. Noll made his debut as a pinch-hitter against the New York Mets on March 30, 2019, grounding out on a high chopper. In his third major league at-bat, on April 3, he worked a bases-loaded walk against Philadelphia Phillies reliever David Robertson for a walkoff win in the ninth inning. On April 24th, 2019, Noll started his first major league game against the Colorado Rockies at Coors Field. He recorded his first major league hit the same day, an RBI double off of Rockies pitcher German Marquez. In 8 games with the Nationals, Noll had a.167 average and 2 RBI. The Nationals finished the 2019 year 93-69, clinching a wild card spot, and eventually winning the World Series over the Houston Astros. Noll was not part of the postseason run, but still won his first world championship.