Jack Sparkes, from Exmouth, came through the academy and made his first-team debut aged sixteen in 2017. He played in thirty-one league games when City were promoted in 2022. Jack left the club after not being offered a new contract at the end of the following season and joined Portsmouth where he was part of a promotion-winning team.   

Jack became a scholar/trainee in 2016 and made his league debut at the start of his second season away at Swindon Town on 12 August 2017. He played his first home game against Lincoln City the following week and scored his first goal against Yeovil Town in the EFL Trophy on 29 August 2017. Jack then appeared in a further two EFL Trophy games, and made one league appearance, during the rest of autumn 2017. He did not play for the first-team again until the League Cup tie against Ipswich Town on 14 August 2018 before going to make four more cup and trophy appearances that season. Jack also had time on loan at Chippenham Town and Salisbury during 2018/19.

Jack started to feature more regularly in the truncated 2019/20 season when he had played twenty-three games before suffering a serious injury against Newport County on Boxing Day. He was not to return until the play-offs when he made a substitute appearance against Northampton Town at Wembley. Jack was then a regular in 2020/21, the season largely played behind closed doors, when he played in fifty games in all competitions. He also scored four goals, including his first in the league at Scunthorpe in March 2021. 

Early in 2021/22 Jack suffered a broken collarbone and, after briefly returning to first team action, joined Torquay United on loan in December 2021 making three appearances and scoring a Boxing Day goal against Yeovil Town. Returning to Exeter, he scored a memorable goal in the 4-3 win over Harrogate on 15 February 2022. Thereafter Jack was to make his 100th Exeter City first-team appearance against Salford City on 12 March 2022 and soon went on to feature in the Exeter team that clinched promotion against Barrow on 26 April 2022. 

Continuing to feature on a regular basis during 2022/23 in League One, Jack appeared in another forty league and cup games before - with his departure already announced ahead of the final game of the season - making a farewell appearance as a substitute against Morecambe on 7 May 2023.

Leaving St James' Park after seven years as a scholar/trainee and professional, Jack agreed terms with Portsmouth ahead of the 2023/24 season. Featuring regularly throughout the season - both as a starter and from the bench - Jack was part of the Pompey team that won promotion in April 2024. With the club strengthening its squad over the summer, he subsequently moved to Peterborough United on a three-year deal in July 2024.