Valid Irish insurance discs will serve as proof of insurance for those driving Irish-registered vehicles in the UK, including Northern Ireland, in the event of a no-deal Brexit.
The decision has been confirmed by the UK Department of Transport following detailed discussions between it and the Motor Insurers' Bureau of Ireland (MIBI).
In advance of the original Brexit deadline of 29 March, the MIBI had cautioned that the Green Card - an internationally recognised insurance document - would be required for all Irish-registered vehicles travelling in the UK, if a no-deal Brexit occurred.
MIBI Chief Executive David Fitzgerald said the development was really positive news and a relief for anyone who needs to travel to the UK and Northern Ireland.
He said: "Valid Irish insurance discs will now serve the same purpose as Green Cards.
"Effectively that negates the need for additional documentation for any Irish-registered vehicles travelling to the UK, including Northern Ireland, in the event of a 'no deal' Brexit."
The MIBI said that in the event of a no-deal Brexit, Green Cards will still be needed for UK-registered vehicles visiting other EU countries, including Ireland.