The 19-year-old, who is on loan from Rangers, hit the Blues’ priceless second goal against gutsy Carrick Rangers at the Loughshore Leisure Arena in a game that will not live long in the memory.
David Healy’s boys were gifted an early opener when Carrick midfielder Thomas Scully poked the ball into his own net.
When McKee produced his party piece before the break, the reigning champions looked home and dry.
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But Rangers hit back in the second half through Jordan Gibson, which made it a nervous final 22 minutes for Healy’s men.
The game was due to take place a week earlier but called off because of NIFL’s Covid guidelines.
Rangers chief Stuart King, whose team are still hovering only five points above 11th-placed Portadown in the league table, introduced captain David Cushley, Reece Glendinning and Lloyd Anderson to his line-up, replacing Corey McMullan, Kyle Cherry and Stewart Nixon.
Blues manager David Healy reshuffled his pack following an unconvincing win over Portadown last time out, handing goalkeeper David Walsh, Kirk Millar, Christy Manzinga and Kyle McClean starting shirts.
It took the Blues only three minutes to forge ahead.
McKee and Christy Manzinga combined before sending Jake Hastie free on the left and, when he drilled in a low cross, midfielder Scully - on loan from Accrington Stanley - poked the ball into his own net.
The visitors almost did it again on 17 minutes.
Kyle McClean’s shot was brilliantly saved by goalkeeper Aaron Hogg and when the ball fell to McKee he looked a certain scorer until Mark Surgenor came in with a great block challenge.
Healy’s boys did strike again eight minutes before the break.
Hastie and Millar worked a clever move with a short corner and when the former Motherwell man drilled in a low cross, McKee scored with a cheeky backheel.
Two minutes later, Manzinga reeled away to celebrate after his bullet header, following a sublime cross from Conor Pepper, thundered past Hogg but the goal was ruled out as the big striker had strayed offside.
Linfield had a big appeal for a spot-kick turned down by referee Christopher Morrison just before the break when Pepper went down under a challenge from Ben Tilney, much to the disgust of the big away support.
Manzinga should have had the Blues out of sight three minutes after the restart.
He was sent clear with a wonderful pass from Millar but, with only Hogg to beat, the striker could only drill the ball against the legs of the big shot-stopper.
Rangers were almost back in it on 65 minutes – with their first meaningful attack.
Scully’s free-kick was met by substitute Stevie Gordon, whose header was hoofed off the line by an alert Chris Shields.
In fact, after Gibson cut the gap, Rangers then came within inches of an equaliser with five minutes left only for substitute Emmett McGuckin’s shot to fizz just wide.
CARRICK RANGERS: Hogg, Surgenor, Ervin, Cushley (E.Kelly, 70), D.Kelly (McGuckin, 46), Glendinning, Gibson, Carson (Gordon, 46), Scully, Tilney, Anderson (Chambers, 76).
Subs (not used): Skeet, Kalla, Waite.
LINFIELD: Walsh, Shields, Callacher, Millar, Manzinga (Vertainen, 76), Hall, McKee (Devine, 76), McClean, Fallon, Pepper (Mulgrew, 62), Hastie (Quinn 76).
Subs (not used): Newberry, Salam, Evans.
REFEREE: Christopher Morrison.