The actor turned 42 that day, while the Russian Victoria's Secret model turned 31 Friday. On Thursday, they celebrated with a slew of celebrity friends at their home in the posh Pacific Palisades coastal community near Los Angeles.
Guests included Alyssa Milano and husband David Bugliari, Aaron Taylor-Johnson and wife and Fifty Shades of Grey director Sam Taylor-Johnson, Sienna Miller—Cooper's co-star in Burnt and American Sniper, comedian Dave Chappelle, Jonah Hill—who appeared with Cooper in War Dogs, and Lady Gaga, who is starring with Cooper in his remake of A Star Is Born.
The guests appeared to be in good spirits as they arrived and some carried gifts. Hill arrived first and left about an hour and a half later, before the guests sang "Happy Birthday," E! News has learned.
Lady Gaga arrived with an unidentified man and performed on piano.
Chappelle also arrived carrying a case that appeared to contain a saxophone. He was the last guest to leave, departing around midnight. Cooper escorted him out and the two said goodbye outside the house.
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A source told E! News Thursday Cooper had "something very special planned for Irina's birthday."
"He already got her some very thoughtful gifts and some of the gifts might just even sparkle," the source said.
In December, Shayk sparked rumors she and Cooper were engaged after she stepped out wearing an emerald and diamond ring. The couple has not commented.
On Friday, Shayk posted on her Instagram page a photo of a frosted cake topped with fresh white flowers and mandarin oranges.
"Thank U everyone for the bday wishes," she wrote.
Cooper and Irina have been together for almost two years. She showcased a baby bump while walking the runway at the 2016 Victoria's Secret Fashion Show in November and multiple sources told E! News she and the actor were expecting their first child.
"Bradley been really supportive and helpful towards Irina," the source told E! News. "They both can't wait to have a baby."
Another source had said in December that the two have already picked a few baby names they like and that they know the sex of their child.
"Bradley and Irina love each other so much and this is not gonna be the only kid—there will be a few more after this one," the source added.
While the two have had some conflicting schedules as they prepare for the arrival of their little one, they made time for each other.
"Bradley been really busy with work and running around back and forth but Irina and him are in constant contact," the first source told E! News. "She is such a cool women and lets him have his space when he needs to work, etc."