West Ham have agreed a £13.5m fee with Bayern Munich for right back Noussair Mazraoui plus £3m in add-ons.
Mazraoui, 26, has spent two seasons at the Allianz Arena, having joined on a free transfer from Ajax in the summer of 2022.
The full-back came through the ranks at Ajax, where he played under current Man United boss Erik ten Hag.
He was also a member of the Morocco team that overcame the odds to reach the semi-final of the 2022 World Cup.
There had been reports of United circling the player but now West Ham are nearing his signature.