David Healy's men beat Ards, while the Seaview game resulted in a win for the home side over PSNI
Linfield will play Crusaders in the final of the Toals County Antrim Shield on January 24th.
The Blues hammered Ards 6-1 in Tuesday night's semi-final at Windsor Park, Andy Waterworth and Paul Smyth both scoring twice.
Ards manager Niall Currie tweeted an apology for the performance, saying, "Everyone associated with the club tonight. Sorry. A lot of changes with Ballinamallard Friday night. 3 games in 6 days no excuse for tonight."
The PSNI gave a better account of themselves in the other semi, eventually going down 4-2 against Crusaders at Seaview.
The Championship club twice came from behind to level it and the Premiership champions needed two late goals to go through.
Here's police manager Ian Campbell.
The Crues showed their delight in making the final-
David Cushley scored twice for the Crues and was named man of the match.
He's now aiming to add to the medals he won in finals with former club, Ballymena.