Paddy Power is closing 57 of its 608 betting shops across the UK and Ireland, with almost 250 jobs at risk following the move.
29 Paddy Power stores in the UK and 28 in the Republic of Ireland will shut following a review by parent company Flutter Entertainment.
The review was performed amid increasing cost pressures and challenging market conditions.
Flutter have said that while some staff impacted by the closures will be offered redeployment, there will be a number of redundancies.
A Flutter UK and Ireland spokesperson said: "We are consulting closely with colleagues and providing support to those affected by these changes.
Flutter, which also owns Betfair and Sky Bet, have said that its high street presence remains a key part of its offering, as it continues to adapt to changing customer trends.
They maintain that the decision was driven by market pressures rather than tax changes, amid speculation of increased gambling taxes in the forthcoming Autumn Budget.
Some branches have already closed following the announcement, with a branch in High Wycombe now permanently shut and boarded up.
It is reported that BOYLE Sports, Ireland's largest independent bookmaker with almost 400 shops across the UK and Ireland, has pledged job interviews to all staff affected by the closures, offering vacancies in customer service, operations, and shop management.
