Drogheda United Having been a non-playing substitute in some matches in 2020, Phillips made his debut for
Drogheda United in a 1–0 loss at home to
Shamrock Rovers on 20 April 2021. The first senior goal of Phillips' career came on 8 May 2021, in a 7–0 win away to
Waterford at the
RSC as the home side fielded their under-19 squad due to a
COVID-19 outbreak in the first team. On 24 October 2021, he scored the only goal of the game as Drogheda beat
Derry City at
United Park. He made 31 appearances in all competitions during the 2021 season, scoring two goals.
Crystal Palace At the end of the season, Phillips had a trial with
Crystal Palace and made a permanent move to the
Premier League club in January 2022, and spent the rest of the
2021–22 season with the club's under-23 team. but was only involved as a non-playing substitute. He was part of the Crystal Palace first-team squad that travelled to Singapore and Australia before the
2022–23 season and started in the friendly games against
Liverpool and
Manchester United. Phillips made his competitive senior debut for Crystal Palace on 23 August 2022, starting in a 2–0 win away to
Oxford United in the
EFL Cup.
Loan to Shrewsbury Town On 29 December 2022, it was announced that Phillips would join
Shrewsbury Town on loan until the end of the season, once the transfer window opened on 1 January 2023. Despite only featuring for half of the season, Phillips was awarded the Young Player of the Season for his efforts. His performances for the
Shrews were described as "immense" by the club's manager
Steve Cotterill.
Loan to Wycombe Wanderers On 11 August 2023, Phillips signed a new contract with Crystal Palace and on the same day also joined
EFL League One club
Wycombe Wanderers on a season long loan deal. Phillips scored his first league goal for the club in a 2–1 loss against local rivals
Reading on 25 November 2023.
Loan to Aberdeen After it was mutually agreed to cut short his loan at Wycombe Wanderers, Phillips joined Scottish club
Aberdeen on 28 January 2024 until the end of the season. On 20 April 2024, he featured in the
Scottish Cup Semi-final at
Hampden Park which ended in heartbreak as he took his side's final penalty in the shootout which was saved by
Joe Hart, sending
Celtic through to the final.
Loan to St Mirren On 21 August 2024, Phillips joined
Scottish Premiership club
St Mirren on a season-long loan deal. He scored 4 goals in 37 appearances in all competitions during his loan season with the club, before being voted the club's Player of the Year at the end of the season.
St Mirren On 22 May 2025 it was announced that Phillips had joined
St Mirren on a permanent deal after the club activated their obligation to buy, following his loan spell, joining on a one year contract with the option of a further season. On 14 December 2025, Phillips played the full match in the
2025 Scottish League Cup final, as his side defeated
Celtic 3–1 at
Hampden Park to win the first trophy of his career and the club's first in 12 years. ==International career==