The strike action is taking place at over 100 stores across the country, including 7 in Tipperary, as part of a row about the company's alleged widespread use of low-hours contracts and its alleged refusal to negotiate the Mandate union.
Around 5 thousand staff are set to mount the pickets at stores from 6am this morning following a ballot of union members.
The company has outlets in Thurles, Nenagh, Roscrea, Clonmel and Tipperary Town.
Jobs Minister Richard Bruton is appealing for both sides in the dispute to start talks.
