At international level, Bîrligea made his full debut for Romania in October 2023, in a 4–0 UEFA Euro qualifier win over Andorra.

Born in Brăila, Bîrligea spent part of his childhood in Constanța, where he started practising young football with local club Metalul.

Bîrligea relocated again at age 12, moving abroad to Italy with his mother and elder sister,[3] and represented the academies of ASD Cantera Ribolla and Palermo.

[9] Two weeks later, he started in a 2–1 home victory over Universitatea Craiova, as his club was crowned national champion one fixture prior to the end of the season.

[12] On 16 February 2023, Bîrligea recorded his European debut by starting in a 0–1 away loss to Lazio in the knockout round play-offs of the UEFA Europa Conference League.

[17][18] Rapid București made a last-minute attempt to hijack the deal,[19] but Bîrligea was officially unveiled by FCSB the following day and handed the number 9 shirt.

[20] Bîrligea made his debut for "the Red-Blues" on 21 September, starting and coming off at half-time in a 1–1 Liga I draw with Petrolul Ploiești at the Steaua Stadium.

Bîrligea made his debut for the Romania national under-21 team on 25 March 2022, equalising late in an eventual 2–1 friendly win against Finland at the Stadionul Arcul de Triumf in Bucharest.