The carrier is also adding two Airbus A330 aircraft for next summer
Aer Lingus is to expand its fleet, with the delivery of at least eight Airbus long-range aircraft from 2019.
The carrier has also announced a further expansion of its wide-body fleet for summer 2018 routes.
An additional two Airbus A330 aircraft will enter service next summer.
Overall, its North Atlantic fleet will be made up 17 aircraft - 13 Airbus A330s and four Boeing B757s - operating up to 34 transatlantic services daily across 15 routes.
In addition to a four times weekly service from Dublin to Seattle in May 2018, a Philadelphia service is to increase from a four times weekly to a daily service from May.
In a statement, the IAG-owned airline says: "Aer Lingus looks forward to the on-going development of hub infrastructure at Dublin Airport which will be required to accommodate this planned expansion.
"The growth in transatlantic operations is a key element of Aer Lingus’ strategy of expanding its Dublin Airport base into a major hub."
While traditionally Aer Lingus connected Ireland and North America, today more than one-third of its transatlantic passengers transit through Dublin connecting with its UK and European network.
It says the "convenience" of US Customs and Border Protection services at Dublin Airport has enhanced the growth of its Dublin operation as a connecting gateway.
Stephen Kavanagh, Aer Lingus CEO commented: "This investment in additional employment and aircraft is testament to the success Aer Lingus has had in growing its transatlantic gateway at Dublin and to the confidence we have in the opportunity to continue to build upon this success.
"2018 will see us continue to offer increased value and choice and to deliver upon our ambition to be the leading value carrier across the North Atlantic".