Liam Lawlor is released from Mountjoy prison
A spokesman for the prison confirmed to ireland.comthat Mr Lawlor had been discharged at 2.10 p.m.
The van speeds past waiting journalists
The prison authorities earlier described Mr Lawlor's stay as having gone "smoothly".
A spokesman said he had been treated "like any other prisoner". However, concerns for Mr Lawlor's safety led prison authorities to hold him in a single cell.
Mr Lawlor was sentenced for a week for failure to provide information to the Flood tribunal.
He served the full seven days of his sentence. As he was jailed for contempt of court and had not been convicted of a criminal offence, he did not qualify for the statutory 25 per cent remission in sentence which applies to prisoners who demonstrate good behaviour.
Mr Lawlor avoided the press and photographers last week when he arrived at Mountjoy in a Garda van after being formally arrested at Ronanstown Garda station.
When Lawlor completed his first week in prison for the same reason in January last year, he wrong-footed the waiting media by having his regular car pick up his bags first and leaving later himself in his less obvious gardener's van.