E! News has all the details on Katy's celebratory day out in Montecito, Calif., where she and Orlando recently purchased a $14.2 million mansion.
A source exclusively tells E! News, "Katy's birthday seemed low key and was a family weekend at home."
On Sunday morning, Katy and Orlando started the day by taking a leisurely walk with their dog to get some fresh air.
"They both seemed happy and relaxed," the eyewitness says. "Katy was dressed casually and comfortably in sweats. She seemed to be enjoying her birthday."
The couple chatted together and watched the little dog run off for a few minutes, but the new parents kept it to just the two of them for her birthday stroll. The source adds, "They left the baby at home and didn't bring her along."
Orlando and Katy are still on a high after welcoming their daughter, Daisy Bloom, on Aug. 26.
Later in the day, some of Katy's family stopped by for a small quiet gathering to honor the American Idol judge.
And the festivities included some bling, of course. Orlando is said to have selected his birthday gift for her at Daniel Gibbings Jewelry in Montecito on Saturday while out shopping.
A source says, "He picked up a little something and had it wrapped up in a bag. He quickly picked it up and brought it back home."
Orlando topped off the day with a sweet note on Instagram, writing, "Happy Birthday my love oh the places we'll go..."
The "Daisy" singer didn't need all that, and had one small ask on her special day. As Katy wrote on Twitter, "my wish is simple: vote."
The whole party took place near Katy's hometown of Santa Barbara. The lovebirds evidently wanted to stay close to the nest, as they bought a new family home last week: a Mediterranean Villa that came complete with a hedge maze and patio with ocean views.
Relive more of Katy and Orlando's cutest moments here.