The 2025 World Junior Ice Hockey Championship Division I consisted of two international under-20 ice hockey tournaments organized by the International Ice Hockey Federation.

For each tier's tournament, the first-placed team was promoted to the next higher division, while the bottom-placed team was relegated to a lower division.

The Division I A tournament was played in Bled, Slovenia, from 9 to 15 December 2024.

GP = Games played; G = Goals; A = Assists; Pts = Points; +/− = P Plus–minus; PIM = Penalties In Minutes Source: IIHF (minimum 40% team's total ice time) TOI = Time on ice (minutes:seconds); GA = Goals against; GAA = Goals against average; Sv% = Save percentage; SO = Shutouts Source: IIHF Source: IIHF The Division I B tournament was played in Tallinn, Estonia, from 11 to 17 January 2025.

GP = Games played; G = Goals; A = Assists; Pts = Points; +/− = P Plus–minus; PIM = Penalties In Minutes Source: IIHF (minimum 40% team's total ice time) TOI = Time on ice (minutes:seconds); GA = Goals against; GAA = Goals against average; Sv% = Save percentage; SO = Shutouts Source: IIHF Source: [IIHF]