The Rangers winger went to Cappielow on an initial one-month deal before Christmas and has done well in his appearances with the Greenock side.
His highlight so far has been scoring the winning goal for them at Livingston on January 18, only their third league success of the 2013/14 and their first on the road.
McKay, who signed a five-year contract with the Light Blues last term, is very much part of Ibrox manager Ally McCoist’s plans in the long term.
But for now he’ll continue assisting Kenny Shiels’ team in its bid to avoid relegation from the Championship.
Ton currently sit eight points adrift of the play-off place and 15 from third-bottom Alloa, albeit they do at least have one more game to play than ninth-placed Cowdenbeath.
McKay was a squad regular at Gers last season and made 41 appearances including 20 starts before he broke his foot in April. He also scored four times.
This term he has just one goal from four substitute outings for the League One leaders, that coming in the Ramsdens Cup against Berwick back in August.
McKay is hopeful staying with Morton will make him a better player when he reports back to Murray Park in the summer.
The 19-year-old told the Evening Times: “First-team football was a big factor in my decision. I really want to play and need to be playing at my age.
“I am happy at Morton so there was no point going back to Rangers and not getting a sniff. If I am out playing games it will benefit me and Rangers in the long run.
“When I go back to Rangers, I will return a better player. I spoke to the manager and he was happy for me to stay out on loan and play first-team games.
“He never said I wouldn’t get a chance at Rangers but I know he has brought in a lot of good players and has a big squad. I am happy to stay at Morton until the end of the season.”
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