An Post said it has reduced its carbon emissions by half compared to 2009 levels.
In its 2025 Sustainability Report, An Post reported that electric vehicles made up more than 50% of its delivery fleet.
So far this year, 575 new, larger EVs have been deployed, 30% of which replaced diesel vans.
The remainder have replaced smaller, first-generation EVs, which had a lower battery range.
The progress has been made while the carrier dealt with "record parcel growth" - up 27% to 73 million items last year.
The report also shows that 95% of An Post's heavy goods vehicles switched from diesel to hydrotreated vegetable oil - a renewable diesel fuel made from plant oils or animal fats.
AnPost services 2.5 million delivery points every working day and up to 1 million customers a week in Post Offices.
It has maintained its fourth position in the world in the International Postal Corporation Sustainability Measurement and Management System.
"It is vital that we are able to move ahead at pace with constructing the ecommerce and postal sorting and delivery infrastructure for the future, to be funded from our own resources, once Government approval is received," said David McRedmond, CEO at An Post.
