Born in Caracal, Ștefănescu joined the academy of Sepsi OSK from Viitorul Cluj, with his former side retaining 50% participation rights in a co-ownership deal.

On 12 July 2019, Ștefănescu played his first Liga I match for Sepsi by coming on as a 65th-minute substitute for István Fülöp in a goalless draw with Voluntari.

[6] He recorded his European debut on 22 July 2021, in a 0–0 away draw with Spartak Trnava counting for the UEFA Europa Conference League second qualifying round.

In March 2024, Rapid shareholders Dan Șucu and Victor Angelescu accused Ștefănescu of intentionally getting booked in a match with Petrolul Ploiești (2–1 away win) so he would be suspended against FCSB—they believed Sepsi and FCSB had already agreed on a deal for his transfer the next summer.

On 14 June 2024, FCSB officially announced the signing of Ștefanescu,[16] with owner Gigi Becali reporting the transfer fee as €1.31 million.