The singer dressed up as Kate Winslet’s character Rose from the Oscar-winning film for her bash.
She shared a series of photographs on Instagram showing her and her guests dancing while wearing life jackets.
A post shared by Adele (@adele) on May 6, 2018 at 4:41pm PDT
“Dirty 30!” Adele wrote in the caption.
“I’m not sure what I’m going to do for the next 30 years as I’ve been blessed beyond words in my life so far.
“Thank you to everyone for coming along for the ride the last 11 years with me and my family and friends for entertaining my super fandom of the Titanic movie. Last night was the best night of my life.
“I’m absolutely f*****, not sure I’ll make it out the house again!”
Comedian and close friend Alan Carr – who married his partner at a wedding officiated by the singer earlier this year – shared a photograph of a life jacket he had taken from the party.
Music producer Mark Ronson also posted an image on Instagram showing his hair and eyebrows dusted with fake ice.
The event prompted criticism from some social media users who branded the theme “inappropriate”.
Responding to Adele’s post, one person wrote: “Love @Adele but having a Titantic themed party, dressing in life jackets there’s just something wrong about it. Thousands of people died. It was a tragic real event.”
Another user added: “Isn’t this kinda/very inappropriate? Adele’s Titanic themed birthday party had them dancing in life jackets…thousands of people actually died.”
However, others praised the party, with one person writing: “Adele had a Titanic themed birthday party. She is wearing Rose’s gown and dancing in a life jacket. I have never loved anything more.”
More from Adele
James Cameron’s 1997 film was based on the true story of the passenger liner RMS Titanic sinking in the North Atlantic Ocean in 1912.
About 1,500 people died in the disaster.