The Bridesmaids star has never spent the festive season away from his mother, and is keen to spend Christmas Day in his hometown of Boyle, Ireland.
But O'Dowd's girlfriend, British TV presenter Dawn Porter, is adamant she wants to be at her family home on the Channel Island of Guernsey for the special day.
O'Dowd tells the Press Association, "Christmas when you're in a relationship is difficult because it turns into a time of negotiation and ironically very little good will.
"So we're trying to work out where we're going to spend it, and whose family is going to have the absolute luxury of our company. I've never spent a Christmas away from my mother, so any move from that is going to be tough because I love Christmas in Boyle."
But O'Dowd admits his partner will probably get her way, adding, "She generally wins because she's brighter than me so we'll just have to see how it plays out."