David Zec was born in Kranj on 5 January 2000 and began at his home-town club Triglav before joining Benfica's academy, where the 1.90-metre centre-back played for the B team. He was registered with the club for the 2019-20 season.

He was loaned to Rukh Lviv in Ukraine in October 2020 and left permanently in July 2021 for Celje, winning the Slovenian title with them before moving to Germany with Holstein Kiel in January 2025. He has been capped by Slovenia.