Walker was booked by referee John Beaton during Hearts’ 2-0 loss at Ibrox following a first-half collision with former Tynecastle team-mate Jason Holt.
The 23-year-old served a two-match ban earlier this season after being found guilty of simulation by the SFA when Beaton awarded him a penalty during Hearts’ opening day clash with Celtic.
That incident came less than 24 hours after Craig Thomson booked Thistle attacker Azeez after the striker went to ground following a challenge from Craig Gordon.
Azeez was going through on goal as the Celtic goalkeeper came rushing out. Thistle were 3-1 down at the time and would eventually lose the match 4-1.