The smitten parents, who are worth an estimated $1 billion, decreed a national holiday to mark the arrival of Princess Gabriella and Prince Jacques on December 10, 2014.
But this year they plan to celebrate the special milestone with a quiet ‘family day’ at home.
“I want to take some pictures, some movies of them, so it’s just going to be a family day,” says Albert, a first-time dad at 57.
The wealthy royal also revealed he has a few gift ideas for his adorable tots, who he and his wife call “bah-bahs” at home.
“I really haven’t decided yet whether to give them something significant, which they’ll keep for years to come, or just give them better toys than they already have in the nursery.
“I suppose I could do both,’ he suggested, adding, “probably should”.
Hopefully, the two little royals will also be celebrating their big day with another momentous occasion – taking their first steps.
“They’ve wanted to walk for some weeks on end now, and they are almost there on their own,” Albert told People magazine a few weeks ago.
“They’ve been pulling themselves upright since late August and you still have to hold their arms, but they’re almost there. By their first birthday, they should be taking their first steps on their own.”
Albert has been spending a lot of time in Paris attending the COP 21 climate summit, alongside other global leaders.
But he said he’d be leaving early so he could be home to celebrate the birthday.
Albert says having the twins has taught him to prioritise what is most important in life.
He says Charlene, 37, has also been busy taking care of her twins, including pulling early-morning shifts.
“She’s very eager to be with her children at all times,” Albert previously told People.
“She’s up with the kids at 6, 6:30 and takes them through the morning. Every day. And she continues work for her foundation and her personal workouts, keeping up with her swimming.
“But really. I don’t think they would be as smiling and happy as they are if she weren’t as good a mother as she is.”