Cannonier first made headlines on 7 May 2019, following his performance as one of the ball boys for Liverpool's 4–0 win over Barcelona in the Champions League semi-final.[8] Liverpool manager Jürgen Klopp had noticed that the Spanish team was often slow at getting in position for set-pieces, so the ball boys from The Academy were instructed to return balls to Liverpool's players as quickly as possible. With 11 minutes to go, Cannonier gave Trent Alexander-Arnold the ball, allowing him to take a quick corner, passing to Divock Origi for the decisive fourth goal,[4] completing one of the most memorable victories in the history of the club. Liverpool went on to beat Tottenham Hotspur 2-0 in the final.[9]
A top scorer with the youth teams
Cannonier started playing in the U18 Premier League in 2020, already scoring his first goal in November that year, in a league game against its former team, Leeds United;[10] however, he saw his season prematurely ended because of a hamstring injury, ruling him out of that year's FA Youth Cup final.[6] He signed his first professional contract for Liverpool in the off-season.[10]
The following season, Cannonier proved to be a prolific goalscorer for Marc Bridge-Wilkinson's Under-18s side,[5][11] as he netted his first hat-trick against Manchester United in August 2021.[6] On 9 April 2022, he scored four goals for the youth team, as they beat his former Leeds team 10–3.[12] By the end of the season, he had also trained with Jürgen Klopp's first-team squad.[13]
Cannonier scored a total of 34 goals in all competitions, including 28 in the U18 Premier League,[14] making him the competition's top scorer as Liverpool finished second in the North group, just behind league winners Manchester City.[15] Having also played a key role in the knock-out stage of the Youth League[11] and made his EFL Trophy debut,[6] the striker ended the season with a new long-term contract in Liverpool.[16]
An ambidextrous footballer, Cannonier mainly plays as a centre-forward, where he proved to be a prolific goalscorer for Liverpool's youth teams. Despite then being below the height standards for this position, he stood out with his skills, movement, determination and positional awareness in front of the goal, allowing him to be regularly decisive.[6][11] During his first years in the academy, he played more as a number 10, but evolved as a striker while keeping his ability to provide assists.[7][11]