*Club domestic league appearances and goals, correct as of 12:00, 8 August 2024 (UTC) ‡ National team caps and goals, correct as of 19:44, 19 June 2024 (UTC)
In May 2021, Gazdag was signed by the Philadelphia Union of Major League Soccer.[4] His two-year contract includes a club option for a third and fourth year for an undisclosed transfer fee, reportedly around $1.8 million.[3][5] On 23 May, he made his Union debut as a substitute in a 1–0 victory at D.C. United.[6] He scored 4 goals in the 2021 season. On 23 July 2022, Gazdag scored his tenth goal of the season for Philadelphia Union,[7][8] which cemented his status as the Union's top scorer. On 27 August 2022, he scored his first career hat trick in the Union’s match against the Colorado Rapids, reaching his sixteenth goal of the MLS season.[9] This propelled him to a top rank (second) among the top scorers in the MLS.[10][11]
He scored his first goal, against Andorra, on 31 March 2021.
On 1 June 2021, Gazdag was included in the final 26-man squad to represent Hungary at the rescheduled UEFA Euro 2020 tournament.[13] He withdrew from the squad on 16 June due to injury without making an appearance.[14]
On 14 May 2024, Gazdag was named in Hungary's squad for UEFA Euro 2024.[17] He made one appearance at the tournament, coming on as an 87th-minute substitute for Barnabás Varga in a 2–0 loss to Germany.[18]