A young goalkeeper from Portadown, Walsh has progressed through the Linfield Academy and has been a regular in the first team panel for the last couple of seasons. He made his first team debut for Linfield away to Warrenpoint Town in a match played behind closed doors due to covid-19 restrictions on November 28, 2020. Walsh was the hero in a penalty shoot-out victory over Cliftonville in a Co. Antrim Shield quarter-final at Solitude in October 2022, saving two spot-kicks. He was previously a Full-Time student on Linfield’s scholarship programme.

As of the end of the 2023-24 season, Walsh has made 21 appearances for Linfield’s senior team. He’s a Northern Ireland Youth International at U15, U17, U19 & U21 level. David has played a significant part in the 2024/2025 season so far, keeping a total of 12 clean sheets so far this season.

Walsh signed a one-year contract extension in January 2025, keeping him at the club until the summer of 2026.