The 2025 Liga 3 format was announced on 10 December, 2024.[1] The tournament will feature three stages, the Regional Stage, Second Stage and the Play-Offs. In the Regional Stage, the 37 teams will be divided into four groups based on geographical location. The top four teams of these groups will advance to the Second Stage. In the Second Stage, 16 teams that advanced from the Regional Stage will be divided into four groups of four. The top two teams of each group will advance to the Play-Offs. The finalists will be promoted to the Liga 2.
Initially, 36 teams were to take part in the league: the 25 best placed teams of each department in the national stage of the 2024 Copa Perú plus the 8 quarter-finalists of the 2024 Torneo de Promoción y Reserva and 3 relegated teams from the 2024 Liga 2.[2] However, in October 2024, Deportivo Municipal suffered revocation of its Liga 2 license and was relegated to the Liga 3, increasing the amount of teams in the Liga 3 from 36 to 37. [3][4]