The tie, scheduled to take place on Sunday 26 January, will be the third Manchester derby of the season.
Holders City won the Women’s Super League fixture 1-0 at the Etihad Stadium in September, but United came out on top in the Continental Cup the following month, running out 2-0 winners thanks to strikes from Katie Zelem and Jess Sigsworth.
It is Casey Stoney’s side’s first involvement in this season’s competition, with teams from the WSL and Championship exempt up until now.
The Reds will be hoping to improve on our performance in the tournament in 2018/19, when we knocked out Brighton & Hove Albion and London Bees, before falling to a 3-2 defeat after extra time at Reading in the quarter-final
Here’s the full draw for the fourth round:
West Ham United v Arsenal
UNITED v Manchester City
Lewes v Billericay Town/Actonians
Charlton Athletic v Chelsea
Everton v London Bees
Burnley v Leicester City
Sheffield United v Birmingham City
London City Lionesses v Reading
Bristol City v Durham
Tottenham Hotspur v Barnsley
Huddersfield Town v Ipswich Town
Southampton v Coventry United
Southampton Women's FC v Crystal Palace
Fylde/Sunderland v Watford
Liverpool v Blackburn Rovers
Aston Villa v Brighton & Hove Albion