The men were discovered hiding inside the bulk hold of a cargo ship in Belview yesterday.
Their ages are not yet known and the ship itself was travelling from France to Ireland.
All eight are said to be in good medical health, but it's still unclear where the men were headed or how they got on board the ship.
The eight men are from Albania but had stowed away on board the bulk carrier in the French port of St Nazaire before it sailed to Belview Port.
Officials alerted gardai, but before they arrived three men fled the ship but were apprehended a short time later.
All eight were arrested and brought to Waterford Garda Station where garda began liaising with their French counterparts and discovered that all were already registered as migrants on European databases.
A Garda Spokesman says it's expected that they will be returned to France today via a ferry from Rosslare to Cherbourg.
In a statement, gardaí said: "Garda Immigration Officers attached to Waterford Garda Station are currently dealing with the males and they will be processed under the immigration law.
"An Garda Síochána continue to investigate all the circumstances of this incident."
