[5] In his third match, against Trinidad and Tobago, he took figures of 4/47, including the wickets of West Indies internationals Jason Mohammed and Rayad Emrit.
[8] In October 2018, Walsh was named in the United States' squad for the 2018 ICC World Cricket League Division Three tournament in Oman.
[13] The United States finished in the top four places in the tournament, therefore gaining One Day International (ODI) status.
[14] Walsh made his ODI debut for the United States on 27 April 2019, against Papua New Guinea, in the tournament's third-place playoff.
[15] In June 2019, he was named in a 30-man training squad for the United States cricket team, ahead of the Regional Finals of the 2018–19 ICC T20 World Cup Americas Qualifier tournament in Bermuda.
[17] In August 2019, he was named in the United States' squad for the Regional Finals of the 2018–19 ICC T20 World Cup Americas Qualifier tournament.