Bank of Ireland has raised €750m by issuing its first green bond.
The banks said the money will be used to fund sustainable projects including green buildings and energy efficiency, renewable energy and clean transportation.
The bond was three times over subscribed.
The lender said green finance was a key objective of its new strategy on responsible and sustainable business.
It commits the firm to working with customers and staff to help them move to a net zero carbon economy by the middle of the century.
"Today is another important milestone on our sustainability journey, with the successful issuance of our inaugural Green Bond," said Mark Spain, Bank of Ireland's Chief Strategy Officer.
"We have made significant progress to date in supporting green loans and mortgages for customers across Ireland and in transforming our own operations and reducing our carbon footprint."
The bank also has a €2bn Sustainable Finance Fund, with €950m of green loans allocated to home owners and businesses.
The firm has also lowered carbon intensity within its own operations by 77% since 2011.