The 2019 IIHF U18 Women's World Championship Division I was three international under-18 women's ice hockey tournaments organized by the International Ice Hockey Federation (IIHF). Divisions I A, I B and I B Qualification represent the second, the third and the fourth tier of competition at the 2019 IIHF World Women's U18 Championship.
The Division I Group A tournament was played in Radenthein, Austria, from 7 to 13 January 2019.
<section begin=Division I A/><section end=Division I A/>
The Division I Group B tournament was played in Dumfries, United Kingdom, from 6 to 12 January 2019.
<section begin=Division I B/><section end=Division I B/>
The Division I Group B Qualification tournament was played in Jaca, Spain, from 12 to 18 January 2019.
<section begin=I B Q 5-7/><section end=I B Q 5-7/>
<section begin=I B Q SF/><section end=I B Q SF/>
<section begin=I B Q FS/>
<section end=I B Q FS/>