PTSB said it will make "significant" reductions of between 0.15% and 0.95% to its personal fixed-rate mortgage products.
The new rates will come into effect from January 17 and be available to both new and existing personal customers.
This is the fourth cut to fixed-rate mortgages that PTSB has announced since December 2023 and the bank said the cuts reflect its commitment to providing strong competition for its mortgage customers.
Rate reductions will apply across all of the fixed-rate terms offered by PTSB - its two-year, three-year, four-year, five-year and seven-year terms.
The bank said the biggest reduction of up to 0.95% will apply to its five-year and seven-year fixed term products, with rates from 3.8% for LTV of 60-80% for mortgages up to €250,000, while certain Green mortgages will see rates reduce by up to 0.7%.
It said the rate cuts will vary depending on the Loan to Value band.
PTSB said that customers whose loan applications have been approved at the old rates but who have not drawn down will automatically benefit from the new, lower rates.
Customers whose applications are at the pre-approval stage will also benefit from the new, lower rates.
Dermot Ryan, Head of Bank Products and Pricing Strategy of PTSB, said the bank is resolutely committed to competing strongly in the mortgage market.
"The combination of these new, lower rates and the quality of our service and our people demonstrates this commitment and our appetite to drive competition for the benefit of the customers we are here to serve," Mr Ryan said.
Banks are under pressure to cut their mortgage rates as the ECB cut euro zone rates four times last year, with more cuts expected this year.
Last November, Bank of Ireland announced it was cutting all of its fixed mortgage rates by 0.5%, while non-bank lender ICS also recently reduced rates.
Earlier this week, Spain's Bankinter said it would launch a full Irish retail banking service, after the expansion of lending through its Avant Money brand.
