The model, fashion blogger and TV presenter had jetted home from LA for the celebration which was held at a Dublin restaurant and attended by friends and family including Game of Thrones actor Liam Cunningham.
Vogue and former Westlife singer Brian split in September after three years of marriage but have remained close friends.
On the day itself Brian tweeted a happy birthday to his ex-wife, “Happy birthday to the beautiful @VogueWilliams you don’t look a day older than 21!!! Xxxxxx” with an image of an elderly lady smoking.
Writing about her birthday in her Sunday World column today, Vogue said, “We had gorgeous food and loads of drinks and my friend Dave Byrne was DJing. He’s so good and it made the night amazing.
“Brian came home for my birthday and it was nice that he was there. We are getting good at this being friends thing and it was great to have him there to celebrate with me.”
She also said that she was “quite looking forward to” her thirties.
“It’s another entire decade of having fun and achieving things I’ve always wanted to achieve.”
She added, “I did envision my life would be slightly different at 30, but everything that happens always does for a reason, so I’m trying to go with it.”
Vogue had been in LA to interview Emilia Carr who is on death row and she said the meeting “really put things into perspective” for her.
Brian previously spoke about how they have remained “great friends” in the wake of their split.
“We’re still great friends, a lot of people have their break-ups and they don’t talk but me and her are genuinely still friends and we still hang out.”