Ruben Amorim's Reds will be in action against Grimsby Town on Wednesday 27 August.
United were the last team out of the hat in the Carabao Cup second-round draw and are facing the League Two outfit at Blundell Park.
Kick-off is at 20:00 BST and the match will be broadcast live in the UK by both ITV and Sky Sports.
The contest comes either side of our Premier League fixtures against Fulham and Burnley, later this month.
Grimsby have announced that the travelling Reds will be located in the Osmond Stand.