The highly-rated teenager, who has captained his country at under-18 level, attracted interest from a number of clubs before putting pen to paper on a deal with the Magpies, initially linking up with Newcastle's under-21 side.
The Irishman, who has represented Republic of Ireland at under-19 level, joined Galway's Academy at the age of 14, progressing through the club's youth ranks before making his first-team debut at the tender age of 16.
Murphy travelled with the Magpies' senior squad to Saudi Arabia during a warm-weather training camp in December 2022 before making his United first-team bow as a substitute during a 5-0 win over Al Hilal in Riyadh.
Alex made his first senior start for Newcastle United during the Magpies' 2-0 Sela Cup win against Fiorentina in August 2023, keeping a clean sheet in front of over 36,000 fans at St. James' Park.
The versatile defender made his Premier League debut during Newcastle's 4-1 win against Chelsea at St. James' Park in November 2023, as well as featuring in the latter stages of the Magpies' 5-1 thrashing of Sheffield United in April 2024, before signing a new long-term contract with the club the following month.