Worrall signed with Nottingham Forest in October 2011, rejecting interest from other local sides Derby County and Leicester City. Worrall joined League Two club Dagenham & Redbridge on 8 January 2016 on a one-month loan deal. He made his professional debut the next day in a third-round FA Cup tie against Everton, which Dagenham & Redbridge lost 2–0, and scored his first professional goal on 23 January in a 2–2 draw away at Newport County. Worrall made his first team debut for Forest on 29 October 2016 at Reading and, despite losing the game 2–0, his performance was praised as "strong" and "decisive" by the Nottingham Post. On 19 November, Worrall started alongside Damien Perquis and Matt Mills in a three-man defence as Forest earned their first away win and clean sheet of the season at Ipswich Town. His performance led to Worrall being included in the Football League's Team of the Week and comparisons to former Forest and England defender Michael Dawson. He was also praised by his manager, Philippe Montanier, who described the centre-back as "strong and tall, but very clever too, tactically". Worrall's performances were also noticed by Premier League clubs, with Everton and Stoke City reportedly tracking the centre-back. On 27 February2017, Worrall signed a three-and-a-half year contract to extend his stay with Nottingham Forest until the year 2020, then later that year after his success with England at the Toulon Tournament a further extension until 2022.
On 19 May 2017 Worrall was called up to the England representative squad for the 2017 Toulon Tournament as a replacement for Charlton Athletic'sEzri Konsa, who had been promoted to the U20 squad for the 2017 FIFA U-20 World Cup. Appointed as the team's captain, Worrall played four times and lifted the trophy as England defended their title on penalties after a 1–1 draw with the Ivory Coast in the final. Worrall was also named as the second-best player of the tournament after teammate David Brooks, who won the award. Following his impressive summer with England, Worrall received his first call-up to the U21 squad on 24 August 2017 for their upcoming qualifying matches against their Dutch and Latvian counterparts. Worrall was, however, left out of the squad against the Dutch and was an unused substitute in his team's 3–0 defeat of Latvia on 5 September.
