The women's 400 metre individual medley competition of the swimming event at the 2015 SEA Games was held on 6 June at the OCBC Aquatic Centre in Kallang, Singapore.

[1] Prior to this competition, the existing Asian and Games records were as follows: The following records were established during the competition: The first round was held on 6 June.

The second round was held on 6 June.

The final was held on 6 June.