A farmer and merchant, he was elected to Dáil Éireann as a Fianna Fáil Teachta Dála (TD) for the Louth constituency at the 1937 general election.
At this election, Pádraig Faulkner, was elected as the running mate of Frank Aiken instead of Walsh for the first-time, who was instead nominated to the Seanad though remained a councillor.
Walsh was also Mayor of Drogheda, and a member of the Irish Volunteers, participating in the 1916 Easter Rising.
From 1957 to 1958 he served as Cathaoirleach of Louth County Council, the first Fianna Fáil member to chair the council since the foundation of Fianna Fáil in 1926.
The Larry J. Walsh cumann in Drogheda is named in his memory.