Sergii “Kiy0o” began his professional career with Quixal, where he won the fifth open qualifier for RES European Masters Fall 2024.

In September 2024, he joined Dragon EC, spending six months with the team. Together they placed 3rd–4th at the LEGION UPEA National League 2024, earning $2,417 in prize money.

At the beginning of 2025, Kiy0o represented ALGO, achieving 5th–8th place at the PGL Bucharest 2025 Europe Open Qualifier 1.

His most notable period came in April 2025, when he joined SKYFURY. There, Kiy0o fully showcased his potential: winning the open qualifier for Galaxy Battle 2025 Phase 1, competing in the main event (placing 20th–22nd), and reaching the playoffs in both ESEA Advanced Season 53 and Season 54, finishing Top 12 in consecutive seasons.

In the fall of 2025, Kiy0o joined Lazer Cats, seeing the team as an opportunity to take the next step in his professional career.