The 33,000 sq ft premises is situated in the Wilton Shopping Centre, just outside the city of Cork, and will open next spring. The store will be refurbished and is set to feature a food hall and Café Revive, alongside a range of clothing. It is expected that Roches staff will transfer to positions at the new M&S store.
Marks and Spencer is keen to expand its presence in Ireland, where the economy is booming. The retailer has said that it is aiming to double its 5% share of the Irish food and drink market.
Altogether, M&S is planning to open 25 new stores in Ireland during the next three years - 12 large outlets and 13 operating under the Simply Food brand.
The company has said that sales growth in the Republic is outstripping that in the UK.
Meanwhile, M&S has confirmed plans to open two further franchises in Hungary - the first outside the capital Budapest.
Stores are to open in Pécs in the south west of the country and in Gyor, in the north west, bringing the total number of Hungarian M&S outlets to eight.