Permanent TSB is cutting the rates on its 4-year fixed rate mortgage product by 0.2%.
The reduction will bring the rate from 2.25% to 2.05% for customers with a Loan To Value (LTV) of less than 80%.
In the case of customers with an LTV between 80% and 90%, the rate will drop from 2.55% to 2.35%.
The new rates will take effect from Monday and will apply to all new home loan customers but not existing customers or new or existing buy to let borrowers.
The development, the latest in the fixed rate mortgage market, is aimed at building on the bank's mortgage offering at a time of heightened competition.
Last month, Bank of Ireland cut its high value fixed green mortgage rate to 1.9%.
Finance Ireland, Haven and Avant Money have also reduced their fixed rates in recent months.
However, it is widely expected that fixed rates across the market will start to rise as the cost of funds on the wholesale market increases.
In March non-bank lender, ICS, increase its fixed rates for new customers and it is likely others will follow suit.
Last year Permanent TSB grew its market share of new mortgage lending from 15.3% to 17.8%.