The women's 4 × 100 metres relay at the 2018 IAAF World U20 Championships was held at Ratina Stadium on 13 and 14 July.

[1] Qualification: First 3 of each heat ( Q ) plus the 2 fastest times ( q ) qualify for the final.

[2][3] The final was held on 14 July at 16:01.

[7]