Walter was born in South Perth^[3] and spent the early years of his life in Western Australia before moving to the Gold Coast at nine years of age.^[4] He began playing junior football for the first time shortly after arriving in Queensland when he signed up to play under-9s for the Palm Beach Currumbin Lions^[5] alongside future Gold Coast Suns teammates Ethan Read and Will Graham.^[6] He grew up a West Coast Eagles supporter but has stated that he always had a soft spot for the Gold Coast Suns throughout his upbringing.^[7] He was educated at renowned sporting school Palm Beach Currumbin State High School and played a starring role in their 2022 AFL Queensland State Championship win.^[8]

Along with football, Walter also competed at the national level in short and long distance running, which included winning in the under-10 national 800m race, but eventually gave up running when football became more serious.^[9] He was invited to take part in the Gold Coast Suns Academy at 12 years of age^[10] and began gaining local prominence two months after his 13th birthday when he was awarded the Gold Coast Junior AFL U14s Player of the Year award in 2018.^[11] In 2019, he was selected to represent Queensland as a bottom ager at the U15 Australian Football Championships and his strong performances in that carnival earned him selection as the centre half-forward in the U15 All-Australian team.^[12]

In May 2021, Walter made his NAB League debut for the Gold Coast Academy at 15 years of age against the Dandenong Stingrays and faced future Suns teammate Mac Andrew.^[13] Six weeks later, he made his senior QAFL debut for Palm Beach Currumbin a month after his 16th birthday and kicked two goals in an impressive performance.^[14] In 2022, Walter was coached by newly arrived Palm Beach Currumbin teammate Liam Jones during his AFL hiatus in which he lived and played in southern Queensland.^[15]

Walter was selected to represent the Allies as a bottom ager in the 2022 U18 National Championships and put together several dominant performances that led to him being named as the starting U18 All-Australian centre half-forward at the conclusion of the tournament.^[16] He was considered a top draft prospect leading into the 2023 season and proved his worth by guiding the Allies to a historic first U18 National Championship win in which the team went undefeated and Walter was subsequently named as the starting U18 All-Australian centre half-forward for a second consecutive year.^[17]

Walter became the second Queensland product after Nick Riewoldt to be drafted with a top three draft selection when the Gold Coast Suns matched a pick three bid from North Melbourne in the 2023 AFL draft.^[18] In January 2024, after impressing many onlookers during his first AFL pre-season, Walter broke his collarbone and subsequently missed the early rounds of the 2024 AFL season.^[19] He made his AFL debut at 18 years of age in round 2 of the 2024 season against the Western Bulldogs in Ballarat.^[20]

Updated to the end of round 19, 2026.^[21]