The move brings the curtain down on an eight year campaign by Seaton who split from crew Matt McGovern after Rio. Seaton had been trialling a number of crew replacements since Rio, as earlier reported by Afloat.ie.
McGovern, also from Belfast, is in talks to find a new sailing partner as he intends to continue for Tokyo too.
According to Royal Cork Yacht Club, Seaton and Guilfoyle will make a formal announcement of the campaign in Crosshaven this Friday. The duo will be looking to build on the Rio top ten finish.
Guilfoyle, an ISAF youth silver medalist in the Laser Radial from 2014, withdrew from the 2016 Mens Laser trial with a back injury.
As Afloat.ie reported in Ireland may field as many as four Olympic 49er campaigns for Tokyo. Read our 49er profile here.