Aberdeen will face Championship side Morton in Glasgow on Saturday, October 22.
The Dons will have to deal with a 300-mile round trip and will have to be up early for the tie.
SPFL officials have confirmed the match will get under way at 12.15pm.
The second semi-final between Rangers and Celtic will start at 2.15pm on Sunday, October 23.
Both games will be shown live on BT Sport.