The Bridesmaids star grew up in Boyle, Roscommon in western Ireland, and local authorities have recognised his success in recent years by handing him the region's highest civic accolade.
In a post on his Twitter.com page to announce the news, he writes, ""Just heard I'm getting the freedom of Roscommon! Woohoo! Not sure what it entails, but I'm presuming maidens are involved!""
He later insisted he is thrilled with the honour, which acknowledges locals who have contributed to their communities.
O'Dowd added, ""Actually genuinely chuffed (pleased).""
The actor, who boosted tourism in his hometown by filming his sitcom Moone Boy in the area, is only the third person to be handed the freedom of the county.