The Irish midfielder is heading back to Brighton for pre-season training.
The draw will be made in Vietnam on Friday.
Stubbs was in charge of the Millers from June 2016 to October 2016.
The left-back is the latest youngster to pen contracts at the club.
There have been changes to the League Cup and FA Cup for next season.
Newell and co are determined to make up for the horror season of 2017-18.
The striker is in discussions with Coventry over a permanent deal.
A look at the landmark dates in Rotherham’s summer.
The left-back had the chance to leave the club last summer.