The Department of Transport has said the first of 26 Green Line Luas trams has been extended by more than 10m, increasing its passenger capacity by 30%.
A further 25 trams are to be extended and are due to enter service in the next 14 months.
Each tram will have two new modules added, which means they will be capable of carrying 408 passengers, up from 319.
In addition to these extended trams, eight new 55m trams are expected to be delivered in 2020, all of which will have a passenger capacity of 408.
The number of journeys on the Luas has increased from 30.5 million in 2013 to 41.8 million in 2018 and the transport company says demand continues to increase, with users complaining of overcrowded trams.
Minister for Transport Shane Ross said: "The Government is committed to improving public transport service as this investment shows.
"I look forward to the better service Luas will be able to provide to green line customers over the coming months as more of the trams are extended."
