The Migos rapper stunned his wife during the celebrations for her 29th birthday when he jumped on the microphone to share the news of his surprise gift.
During the bash at Los Angeles' River Studios, Offset shared a video on a large screen of the abode in the Dominican Republic, which boasts a swimming pool on its roof.
In video footage circulated online, he said: "I done bought you the biggest diamonds you could get, I done bought you everything, so this year I wanted to buy something that means something… You gave me my beautiful son...
“I bought you a house in DR.
“I spent some millions on this, right here on the ocean."
Guests at the dancehall-themed bash included Tiffany Haddish, Winnie Harlow, Teyana Taylor, 2 Chainz, Lizzo, Snoop Dogg, Taraji P. Henson, Chance the Rapper, Karrueche Tran, Larsa Pippen and Trey Songz.
In keeping with the Caribbean theme, the food served included jerk chicken, oxtail, rice and plantain, and the guests were kept refreshed with tequila and vodka cocktails.
The 'Bodak Yellow' hitmaker gave birth to her and Offset's son last month and she recently admitted she "lost so much blood" during the "crazy" delivery.
Speaking on her Instagram Story as she hit back at those who claim she has already had surgery to snap back into shape, Cardi - who also has three-year-old daughter Kulture with her spouse - said: “Everybody is like ‘Cardi you so snatched, what did you do, you did lipo, you had a tummy tuck?’
“You cannot do surgery after you give birth, especially me, I lost so much blood, guys. One day, I’m going to talk to you guys about my crazy-a** delivery.”
Cardi went on to share a few poses she’s perfected in an effort to conceal parts of her post-baby body, and told her followers not to rush getting back into shape.
She added: “F*** it, take your f****** time, it’s really hard dealing with kids, especially when you do two kids after you give birth.”