MacKay, who is the regular presenter of STV's News at Six, got the injury in a clash of heads during a seven-a-side football match involving staff of the Glasgow-based station after his broadcast last Thursday evening.
STV bosses immediately ordered him off air until the colourful purple and yellow bruise around his swollen left eye had died down.
The keen footballer explained his absence from News at Six on his STV online video blog the Real MacKay, which he has renamed the Real Black-Eye.
The blog also shows him having the black eye covered up by a make-up artist in a bid to reclaim his news hotseat from Louise White.
Pointing at his eye, he said the freak accident had happened during a friendly game in Glasgow as he and a rival player went in for a tackle head-on.
He said: "I know a lot of you were very excited on Friday night to see Louise presenting again and probably thought 'we're back to the old ways', but don't get carried away, there was a reason I wasn't presenting the news. There's also a reason why I'm standing in profile, and basically that's it.
"It was a challenge at football, a clash of heads and I ended up like this. On Friday, it was right out and so I couldn't (appear] on Friday.
"There is a lesson here. News presenters shouldn't play contact sports.
"You want to see the other guy, by the way – there's not a mark on him."
MacKay, 45, said he hoped to return to the screen soon.