A technically gifted player, Grealish plays as a winger (normally on the left flank, a position which allows him to cut inside onto his stronger right foot) or attacking midfielder, and has been noted for his ability to run and dribble past defenders. Bryan Jones, Aston Villa's former academy director, likened his playing style to that of Nottingham Forest winger John Robertson, citing his "ability to just ghost past people". During his time with Manchester City, he was occasionally also used in a central attacking role as a false 9 by manager Pep Guardiola. When writing for The Athletic in 2019, sports journalist Michael Cox described Grealish as an "old-school player", due to his playing style. Grealish has also been praised for his professionalism by those who have managed him, with Dean Smith calling him "a really good professional" and Pep Guardiola commenting in 2023 that he was "impressed with how professional" he was. Despite not being gifted with exceptional speed, he is an agile player who possesses quick foot-work, a good change of pace, and excellent balance on the ball, as a result of his low centre of gravity. As a consequence of his nimble movement, Grealish has notably been on the receiving end of heavier, more physical challenges from opposing players. Shaun Derry, his manager at Notts County, highlighted this, following fixtures against Sheffield United and Stevenage in early 2014 and called for more official protection. In a 2014 match for Aston Villa against Hull City at Villa Park, a number of fouls committed against Grealish resulted in three Hull players receiving yellow cards within just a 15-minute period. Grealish wears child-sized shin pads whilst playing, in order to maintain his ability to control the ball effectively. He wears his football socks rolled down due to superstition, which has led to referees warning him to pull them up. In addition to his ball skills, Grealish is also known for his defensive work-rate and intelligent movement, as well as his ability to create chances for his teammates as a playmaker.

Grealish has frequently been compared to Paul Gascoigne and David Beckham for his talent, perceived hedonism, and popularity in England. Shaun Wright-Phillips has voiced his belief that Grealish is "of a similar mould" to Gascoigne, with Wayne Rooney, Bryan Robson, Troy Deeney and Tim Sherwood all expressing similar views. However, others argued that such comparisons should not be made, suggesting that they would prevent Grealish from developing into his own player. Grealish himself has stated that he would "love to be like Gazza [Paul Gascoigne]", adding that Gascoigne "played with such joy" – a trait that Grealish said in 2020 he would like to emulate. In February 2021, in an interview with Talksport, former Aston Villa teammate Emiliano Martínez described Grealish as "the most talented player [he had] ever seen" and expressed surprise that he had not played more games for England. Martínez went on to say: "he never gives the ball away. When I see Grealish running, it's always a shot on target or a corner for us. He will drive past two or three players". Martínez also drew comparisons of Grealish to his Argentina teammate, Lionel Messi.

From English Wikipedia, CC BY-SA