In October 2019, he was named in Pakistan's
Test squad for their series
against Australia. In November 2019, he played in the three-day warm-up match for Pakistan against
Australia A. He made his Test debut for Pakistan, against
Australia, on 21 November 2019. His debut was appreciated by many senior cricketers, such as former Pakistan fast bowler
Waqar Younis and former England captain
Michael Vaughan, the latter being impressed by the 16-year-old touching 147 km/h, or 91.3 mph, in his first ever over. Australian batsman
David Warner praised Naseem’s pace, control, and aggression after the teenager repeatedly troubled him despite going wicketless in his debut innings, highlighted by a disallowed caught-behind dismissal due to a no-ball. Warner described Naseem as an exceptional talent capable of replicating the impact
Mohammad Amir had early in his career. In December 2019, he was named in Pakistan's Test squad for the two-match series
against Sri Lanka. In the second match, he took his first
five-wicket haul in Test cricket. At the age of 16 years and 307 days, he became the youngest
fast bowler, and the second-youngest among all bowlers, to take a five-wicket haul in a Test match. He was initially named in Pakistan's squad for the
2020 Under-19 Cricket World Cup, but after his impressive start in Test cricket, he was withdrawn from the U19 team. In January 2020, the
Pakistan Cricket Board (PCB) issued a statement on Naseem being withdrawn from their U19 squad. They reiterated that it was due to cricketing reasons, and not concerns about his age, stating they have checked and verified the ages of all cricketers who could play in their U19 team. On 9 February 2020, in the first Test
against Bangladesh, at the age of 16 years and 359 days, he became the youngest bowler to take a Test
hat-trick. In May 2020, the PCB awarded him a central contract ahead of the 2020–21 season. In June 2020, he was named in a 29-man squad for Pakistan's
tour to England during the
COVID-19 pandemic. In July, he was shortlisted for Pakistan's 20-man squad for the Test matches against England. On 21 August, he was named in Pakistan's
Twenty20 International (T20I) squad, also for the series against England. In November 2020, he was named in Pakistan's 35-man squad for their
tour to New Zealand. In October 2021, he was named in the
Pakistan Shaheens squad for their tour of Sri Lanka. In August 2022, he was named in Pakistan's ODI squad, for their
tour of the Netherlands. He made his ODI debut on 16 August 2022, for Pakistan, against the
Netherlands. During the last ODI, Naseem took his maiden wicket in ODIs. Later the same month, he was named in Pakistan's T20I squad for the
2022 Asia Cup. He made his T20I debut on 28 August 2022, against
India. On 7 September 2022, Naseem Shah made history by delivering 2
sixes against
Afghanistan to save
Pakistan from a defeat and help qualify for the finals. In September 2022, he was named in Pakistan's T20I squad for
England's tour of Pakistan. In October 2022, Naseem was named in Pakistan’s T20I squad for the
Tri-Series in New Zealand. Later in October, Naseem was named in Pakistan's T20I squad for the
2022 ICC Men's T20 World Cup. He had a proficient run in the World Cup and helped Pakistan qualify for the
2022 ICC Men's T20 World Cup Final, but lost it. In November 2022, he was named in Pakistan's Test squad for
England's tour of Pakistan. After the first match, Naseem suffered a shoulder injury that ruled him out of the series. In December 2022, he was named in Pakistan’s Test squad for
New Zealand's tour of Pakistan and later in the ODI squad in January 2023. In the first ODI against New Zealand, Naseem took his second fifer in ODIs and a consecutive fifer. In September, he was ruled out of 2023 World Cup due to an injury. In May 2024, he was named in Pakistan’s squad for the
2024 ICC Men's T20 World Cup tournament. == Playing style ==