The increase from the traditional three subs per game has been rubber-stamped by the SPFL ahead of the return from the winter break after it was supported by 75 per cent of top flight clubs.
Celtic’s game against Hibs on Monday will be the first to adopt the change, which will also allow for up nine players to be named on the bench, and it will remain in place for the remainder of the season.
It marks a return to the system used throughout the 2020-21 season, when clubs approved an increase to five replacements with no more than three stoppages, excluding the interval, in order to protect player welfare amid the coronavirus pandemic.
It reverted to three at the start of the current campaign after some clubs expressed concern over how the change benefitted the bigger sides with superior squad depth.
However, with a heavy fixture schedule to come after the break, and concern over Covid isolation rules and possible postponements, clubs have now come around to the move recommended by Ange Postecoglou last month.
The use of up to five substitutes is already permitted in League 2 and the SPFL is consulting with Championship and League 1 clubs over the position in their divisions.
A SPFL spokesman said: “FIFA has allowed each league to determine its own rules regarding substitutes since the Covid-19 pandemic began.
“As a members’ organisation, it is key that clubs in each division are able to make decisions on issues such as this for themselves.”