Immigration enforcement officers went to Enniskillen’s registry office in Townhall Street around 2 pm on Monday following a tip-off.
They arrested the men after checks revealed they had entered the country illegally having travelled from Dublin.
A 24-year-old Estonian woman from Dublin was arrested and released.
Her release was dependent on her voluntarily agreeing to leave Northern Ireland.
She had been due to “marry” one of the men who was 29 years old.
The two other men, aged 26 and 27, were present at the registry office to act as witnesses.
All three were arrested for entering the UK illegally.
They are currently in the Home Office detention centre in Larne while steps are taken to remove them from Northern Ireland.
Mike Golden for Home Office Immigration Enforcement, said: “We are carrying out frequent operations in Northern Ireland to crack down on suspected sham weddings.
“Where we receive information that a wedding may be suspicious we will investigate.”