Thomas joined Leicester City in 2008 after impressing for local side Riverside FC and initially hoped to become a striker after being inspired by Arsenal legend Thierry Henry. However, by the time he was playing for City's Under-14s side, Thomas was impressing many onlookers with his displays on the left for the young Foxes and now primarily plays at left-back.
Over recent years, meanwhile, the enterprising youngster became an England youth international after making his Under-18s debut in 2018 and going on to appear at the 2019 U19s UAE Sports Chain Cup in Dubai. Soon a regular with England's Under-21s, he played twice for the Young Lions at the 2023 U21 European Championships - eventually winning the tournament.
In the summer of 2018, he was nominated for the Club's Young Player of the Season prize and went on to become an established member of Leicester's Development Squad during the 2019/20 season.
Thomas then signed a new deal at King Power Stadium, until 2021, and made his full debut for the Foxes - proving an assist for Ayoze Pérez - during the 2-0 Premier League win over Sheffield United on 16 July, 2020.
After scooping the Leicester City's Development Squad Player of the Season award at the end of the 2019/20 season, meanwhile, Thomas agreed another new, long-term deal at the Football Club.
He continued to be a valuable member of the squad in 2020/21, too, scoring his maiden senior goal for the Club in a 3-3 draw at SC Braga in November, enough to seal qualification from Group G.
The Foxes would go on to secure another fifth-placed finish in the Premier League, while Thomas started for Leicester at Wembley Stadium in May 2021 as City finally lifted the Emirates FA Cup for the first time in the Club's history.
He also came off the bench at the national stadium three months later to help the Foxes win the FA Community Shield. Another 33 outings for Leicester in 2021/22 took his overall tally over 60 as City reached the semi-finals of the UEFA Europa Conference League, eventually losing to AS Roma.
The following campaign proved to be a tough one, with City relegated from the Premier League. Thomas himself played 24 times in league and cup, before two loans spells in the 2023/24 season.
After spending the first six months at Premier League Sheffield United, making 13 appearances, the defender’s second half of the season took him to Teesside and a spell at Middlesbrough under Michael Carrick.
Although unable to reach the Sky Bet Championship play-offs, a positive season at Riverside Stadium concluded with a 3-1 home victory over Watford, having dispatched Cardiff City 4-1 a week earlier.
The former England Under-21s international started both of those successes, playing 12 Championship matches in all for eighth-placed Boro.