"We are ecstatic to announce the birth of our son! Everyone is happy, healthy and doing wonderful. Thank you for all your love and well wishes!!" the couple said in a statement posted on Spears' Web site.
Spears' Web site includes an option for fans to "Send Your Best Wishes" to the couple. The proclamation, "It's a Boy!" sits beneath a photo of Spears and Federline kissing.
The baby was born Wednesday by Caesarean section at the UCLA Medical Center in Santa Monica, Calif., with Federline by Spears' side in the delivery room, Us Weekly reported.
It is the first child for the 23-year-old pop star and Federline, a former backup dancer. Federline, 27, has two children with ex-girlfriend Shar Jackson (search).
As far as names go, Spears recently told Elle magazine that for a boy she loves the names Sean Preston or London Preston.
Us Weekly's sources had the singer set on Preston Michael Spears Federline.
The magazine reported that Spears and Federline arrived at the hospital just before 6 a.m. Wednesday and the singer was taken into the delivery room about 12:15 p.m. The baby arrived just before 1 p.m., according to Us Weekly.
Spears had experienced early labor pains on Sept. 9, Us reported, and had spent an uncomfortable weekend in bed.
The pop star told Elle she didn't want to go through the pain of natural childbirth.
"I have a feeling I'm going to have an operation. I don't know why. But I hope so. I don't want to go through the pain," she said. "My mom said giving birth was the most excruciating pain she's ever gone through in her life. So... if [a Caesarean] doesn't happen, I'll be like 'Epidural, please!'"
Spears added, "Hopefully my athletic abilities will take over. Kevin's going to hold my hand."
The couple wed last year, only months after Spears' 55-hour marriage to childhood friend Jason Alexander, and the birth of Federline's second child with Jackson.
On Thursday, Spears released her new fragrance, "Fantasy." She says it was created with "all kinds of enchanting scents" including "lush red lychee" and even a "hint of cupcakes, white chocolate and jasmine."
The Associated Press contributed to this report.