During the 2017 season he appeared in all fourteen of Michigan's regular season matches as Michigan repeated as PDL Central Conference Great Lakes Division champions scoring one goal. He also played in Michigan's lone PDL Playoffs match. During the 2017 Souahy appeared in two of Michigan's U.S. Open Cup matches including defeating professional side Indy Eleven of the NASL. On January 15 Souahy signed his first professional contract with United Soccer League side Louisville City FC. After a preseason injury he would make his professional debut on April 22 against Atlanta United 2. Starting the match in place of an injured Pat McMahon. He appeared in 19 of Louisville's 34 league matches including 11 of Louisville last 17 as he slowly became a starter as the season progressed. He scored his first professional goal on September 9 against Pittsburgh and scored three goals during league competition. He also made his first appearance in the U.S. Open Cup as a professional when he was brought on as a substitute against the Long Island Rough Riders. He went on to appear in two of Louisville's five U.S. Open Cup matches without scoring as Louisville reached the quarter finals of the competition for the first time in its history. Souahy also appeared in all four of Louisville's USL Cup playoff matches as he and Louisville went on to win the USL Cup Final against Phoenix. Louisville City FC