The women's 4 × 400 metres relay event at the 2021 European Athletics U23 Championships was held in Tallinn, Estonia, at Kadriorg Stadium on 11 July.

[1] Prior to the competition, the records were as follows: Qualification rule: First 3 in each heat (Q) and the next 2 fastest (q) advance to the Final.

[2][3][4] [5]