The highly rated 19-year old defender has agreed to join Tommy Craig’s side until the end of the season.
This will be Plummer’s second loan spell after he joined Oldham Athletic on a youth loan for five weeks in November 2013.
He made his professional debut on 1 December against Bradford City – one of three appearances he made for the Latics.
“This is an exciting development opportunity for Ellis, the experience of playing in the Scottish Premier League will be of huge benefit to him,” said Head of Elite Development Squad, Patrick Vieira.
“I’m looking forward to seeing the progress he makes up in Scotland, and we wish Ellis and St Mirren well for the coming season.”
Plummer was nominated for the Academy Player of the Year award back in July 2013 and turned out on 17 occasions for Vieira’s side last season.
St Mirren, who play at the 8,023 capacity St Mirren Park, have been a Scottish Premier League side since promotion from the Championship in 2006.
The Buddies finished in eighth place last year and they won the Scottish League Cup in the previous campaign.
Their league season gets under way with an away trip to Motherwell on Saturday 9 August.
We’ll keep you updated with Ellis’s progress in our weekly Loan Watch series when the season kicks off.
