McKinnon was charged with rough conduct for a high, late bump on Fremantle star Kiara Bowers in the second quarter of Adelaide's preliminary-final win.
The incident was graded as careless conduct, with medium impact and high contact, drawing a one-game suspension.
The Crows, represented by Samuel McDonough, argued McKinnon's contact was low impact in a bid to have the penalty downgraded.
Tribunal jury members Shane Wakelin and Stephen Jurica, with chair Renee Enbom QC, deliberated for almost 45 minutes before upholding the medium impact grading.
They agreed with Andrew Woods, representing the AFL, the potential for the bump to cause further injury, despite Bowers quickly jumping to her feet, justified the medium grading.
McDonough, with McKinnon in tears next to him, then submitted under "exceptional circumstances", the tribunal should give the ruck a penalty of less than one game.
He cited the 20-year-old's prior clean record and that she was playing in her first grand final.
Woods argued neither factor counted as exceptional and compelling circumstances and after 14 minutes of deliberation, the tribunal upheld the penalty.
McKinnon joins Katie Brennan among the players to be suspended for an AFLW grand final after she missed the Western Bulldogs' 2018 triumph.
Fremantle's medical report noted Bowers was reviewed for concussion at the end of the quarter.
But she did not receive an on-field immediate assessment, did not leave the ground as a result of the incident, returned to play and required no further or ongoing treatment.
McKinnon described the contact as "brushing past" Bowers and said she "felt minimal contact down the side" of her arm, initially believing her contact had been late but not high.
McDonough cited the "low" velocity and that McKinnon also made significant contact with an off-balance Bowers' torso, rather than her head alone, which contributed to her going to ground.
The Crows leaned heavily on GPS evidence from their high-performance manager Jordan Sellar, noting McKinnon had approached Bowers at 18kph - 69 per cent of her top speed.
McDonough also said McKinnon was involved in 47 "direct impacts" in the match and the Bowers contact was the 39th in severity.
Woods described the GPS tracker as a "hamfisted metric" and stressed the tribunal needed to assess the vision in "real time".
Adelaide also unsuccessfuly cited the example of Brisbane's Ruby Svarc having a one-match suspension for a high bump on Collingwood's Jaimee Lambert downgraded.
