The 2023 IIHF U18 World Championship Division I was two international under-18 ice hockey tournaments organised by the International Ice Hockey Federation. The Division I A and Division I B tournaments represent the second and the third tier of the IIHF World U18 Championship.
In the 'A' tournament Kazakhstan clinched the championship (and promotion) on the final day with a victory over the hosts France, while France finished last and were relegated. In the 'B' tournament Austria clinched the championship (and promotion) on the final day with a victory over South Korea before the hosts game against Italy. Their only loss was Poland's only win despite high hopes of an improved roster with a new coach, but were relegated.
The Division I A tournament was played in Angers, France, from 23 to 29 April 2023.
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<small>All times are local (UTC+2).</small>
The Division I B tournament was played in Bled, Slovenia, from 10 to 16 April 2023.
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<small>All times are local (UTC+2).</small>