Clubs in the cinch Championship will be permitted to use five substitues in league matches for the rest of the season.
It follows a vote to increase the number of changes allowed per game in a bid to offset the congested fixture schedule, given the possibility of postponements due to weather conditions or Covid-19.
Benches will now be permitted to carry nine substitues when the rules kick into place from this weekend.
Clubs in League One have also agreed to the move.
Earlier this month, Premiership clubs voted to introduce the rule and the use of up to five substitutes is already permitted in League 2.
An SPFL spokesman said: “Discussions have been ongoing in recent weeks with cinch Championship and cinch League 1 clubs about the potential rule change.
“As a members’ organisation, it is important that clubs in each division are able to make decisions on issues like this for themselves.”
FIFA has allowed each league to determine its own rules regarding substitutes since the Covid-19 pandemic began.
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