In June 2009, aged 15, Topley made the headlines when he was injured bowling in the nets at Loughborough University to England batsman Kevin Pietersen. Pietersen flat drove a delivery, which ended up striking Topley on the side of the head, knocking him to the ground. He was taken to Leicester Royal Infirmary where he required stitches to his ear and was kept in hospital overnight. Following the incident, Pietersen, whom Topley cited as his favourite player, gave the youngster his cricket bat with his signature on. A product of the Essex youth cricket system, Topley made his first-class debut for Essex against Cambridge MCCU in the 2011 season. He impressed on County Championship debut against Kent, taking his maiden five wicket haul when he took figures of 5/46 in Kent's second-innings of the match. In the following championship match against Middlesex he his second five wicket haul, with figures of 5/64 in Middlesex's first-innings. In May 2011, he signed a one-year professional contract with Essex. That month also saw Topley make his List A debut against the Unicorns in the Clydesdale Bank 40, with Topley claiming his maiden wicket in that format, that of Robin Lett. Mid-season Topley took a break from county cricket to return to Royal Hospital School to revise for his summer exams. However, during his break he was called up to play for England Under-19s for their Youth One Day International series against South Africa Under-19s. He returned to action for Essex in August, to date he has played two List A matches and nine first-class matches. He has made a good start to his first-class career, taking to date 34 wickets at an average of 23.55. The start to his career drew praise from former England captainMichael Vaughan, who stated that Topley could become a future Test cricketer. On 1 September 2015, Hampshire County Cricket Club confirmed the signing of Topley from Essex at the end of the 2015 season. At the end of the 2018 season and yet another stress fracture, Topley underwent back surgery.
International career
He made his Twenty20 International debut against Australia on 31 August 2015 and his One Day International debut, also against Australia, on 13 September 2015, taking figures of 0-33. He kept his place in the ODI side for the series against Pakistan and played in all four matches. He picked up his first international wickets in the first match and finished with figures of 3-26, although it wasn't enough to prevent an England defeat. He had picked up one wicket in each of the next three matches, with England winning all three games. He played in the 1st T20 international between the two sides, and finished with figures of 3-24. He continued his role in the ODI side for the tour of South Africa, and again played every game in the series. He took figures of 1-43 in the first game, as England won by 39 runs on the DL Method. In the next game he took figures of 4-50 to help England to back to back wins. England lost the next three games of the series, although Topley performed well, taking figures of 2-39 in the fourth match of the series and 3-41 in the final match, which South Africa won by 5 wickets. He played in both T20 internationals, although he didn't take a wicket in either game. He kept his place in the England side for the T20 World Cup, but was expensive in the first game against the West Indies, taking figures of 1-22 in 2.1 overs. He was expensive in the next match against South Africa, bowling two overs for 33 runs. He was replaced in the side by Liam Plunkett and did not play in the tournament again. Topley was part of that successful T20 squad that was defeated in the World Cup Final in India, but upon returning home was found to have a stress fracture in his back. On 29 May 2020, Topley was named in a 55-man group of players to begin training ahead of international fixtures starting in England following the COVID-19 pandemic. On 9 July 2020, Topley was included in England's 24-man squad to start training behind closed doors for the ODI series against Ireland. On 27 July 2020, Topley was named in England's squad for the ODI series.
