Lending by mortgage specialist ICS Mortgages rose 143% last year compared to 2020.
In total, the non-bank lender lent more than €530m during the year, increasing to over €1 billion its total loan book.
It brings to 5.05% the company's estimated share of the Irish mortgage market.
"As a majority-Irish owned non-bank lender in the mortgage market, we are purely focused on providing mortgages and on delivering real value to our customers via market-leading competitive rates and product innovation," said chief executive Fergal McGrath.
"We are really pleased that Irish consumers have responded to our offerings in such growing numbers."
ICS is now seeking to capture 10% of the mortgage lending market here over the next three years.
Bank of Ireland sold the ICS brand to Dublin headquartered Dilosk DAC in 2013.
The company has since become a leading provider of owner-occupier and buy-to-let residential mortgages.
In August ICS reduced some of its rates below 2% as competition in the market intensified.
The reduction made it only the second lender here, after Avant Money, to reduce rates below the 2% threshold.