Harold spends much of his time in France, other then visiting New York on a few occasions to see Blair. At the end of the series, he adopts Cambodian twins named Ying and Yang Waldorf.
In Pilot, Blair tells Serena that Harold left Eleanor for a man. In Blair Waldorf Must Pie, Blair is excited that Harold is coming to Thanksgiving dinner, as it's their ritual. Flashbacks from the prior year show Blair happily helping her father make dinner, but also show the tension between Harold and Eleanor. In present day, Blair is devastated when Eleanor uninvites Harold behind her back and he doesn't come. Later, Eleanor tells Blair that Harold sent her divorce papers and Blair says she can't be too surprised since he's living in Paris with a man.
Harold makes his first appearance in Roman Holiday when he comes back to Manhattan for Christmas. He brings along Roman, much to the disappointment of Blair. While there, Blair schemes to break them up but it doesn't work. When Harold finds out what she did, Eleanor confesses to him that while Blair likes to act grown up, she still needs her dad. As part of her Christmas present, he shows her a DVD of his house in France and reveals he's having a room decorated just for her.
In A Thin Line Between Chuck and Nate, Eleanor suggests Blair go visit Harold to take a break and relax. Blair originally says no, but after being abandoned by everyone, decides she wants to spend a semester living with him. But before she can leave, Serena convinces her to stay.
In Much 'I Do' About Nothing, Blair says she's spending part of the summer in France with Harold and Roman.
Harold returns in The Magnificent Archibalds as a surprise for Blair on Thanksgiving. Eleanor says Harold had to approve of Cyrus as a suitable stepfather to Blair before she could marry him, and he brings Blair his famous pumpkin pie. In You've Got Yale!, Harold and Roman come to the city to celebrate Blair's hopeful acceptance to Yale. They bring her a bulldog named Handsome and make her breakfast, all the colors of Yale. They plan to attend the opera that evening and do. After Blair spreads a rumor about Rachel and get expelled from Constance, Harold plans to fight Blair's expulsion in Carrnal Knowledge. He crashes a school board meeting and after Rachel is fired, he overhears Blair bragging about how she got the evidence she needed just in time to save herself. Disappointed in his daughter, Harold heads back to France.
Harold returns for his final appearance for Blair and Louis' wedding in G.G. He proudly walks Blair down the aisle with Cyrus on her other side.
- Eleanor Waldorf (ex-wife)
- Roman Garrel (husband)
- He was married to Eleanor for almost twenty years and their happiest time of year was the holidays.
- He calls Blair "Blair Bear".
- His famous pumpkin pie recipe was actually created by Bobby Flay.
- He attended Yale University, which sparked Blair's interest in going there.
- He owns a chateau with a vineyard in Lyon with Roman. They own a cat named Cat, like in Breakfast at Tiffany's.