The 2025-2026 BUL1 consists of a double round robin format where each BUL1 team plays Home-Away matches with the other 15 BUL1 teams, for a total of 30 regular season matches per team. At the end of regular season, the top 6 teams play in the Championship group, teams placed 7th through 10th place teams play in the UEFA Europa Conference League (UEFAECL) group, and teams placed 11th through 16th place play in the Relegation group. In the Championship and Relegation rounds, each team plays 1 match against the other 5 teams in their group for 5 more matches (35 total per team). In the UEFAECL group, each teams play Home/Away matches against the other 3 teams in their group for 6 more matches (36 total per team). Table ranking ties are broken by (1) head-to-head points, (2) head-to-head goal difference, (3) head-to-head goals scored, (4) head-to-head away goals scored (if only 2 teams), (5) goal difference, (6) total goals scored, (7) Fair-play ranking, then (8) a drawing.

Upon completion of the 2025-2026 BUL1 Championship and UEFAECL Playoffs rounds, the 3rd place Championship team enters into Home/Away highest aggregate goals wins matches against the 1st place UEFAECL Playoffs team.

At the end of the 2025-2026 BUL1 Relegation Round, the 7th and 8th place teams will be relegated to BUL2, and the 5th and 5th place teams will enter into a Promotion/Relegation with the 3rd and 4th place BUL2 teams.