Derek Jeter is a father of four!

The retired MLB player revealed via Twitter Monday that he and his wife, Hannah Jeter, secretly welcomed baby No. 4.

“Kaius Green Jeter 5-5-23,” wrote the former New York Yankees shortstop, who did not previously announce his expanding family.

Derek, 48, and Hannah, 33, have been married since 2016 and are also the parents of three daughters.

The couple welcomed Bella, 5, Story, 4, and River, 1, in 2017, 2019 and 2021, respectively.

Becoming a girl dad brought out “a whole other side” of Derek, he told “Extra” in July 2022.

“I’m getting my nails painted and makeup on my face, dresses,” he explained.

“The mornings are early. Getting them up — they’re not in school right now — but dropping them off at school, picking them up. Tennis lessons, ballet lessons.”

The former athlete noted that the little ones “have no idea” about his baseball fame despite knowing he played for the Yankees and occasionally seeing him on TV.

“But other than that, they have no idea,” he said. “And I like it that way.”

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Derek retired in 2014, subsequently moving to Miami with Hannah. The duo have kept their daughters’ lives private, with the girls making few public appearances over the years.

In September 2019, Bella and Story watched their dad’s Baseball Hall of Fame induction in matching blue dresses.

Hannah gave rare insight into her motherhood experience two months later, telling Editorialist Magazine that she is often “covered in paint and glue” while hanging at home with her kids.

The former “Project Runway: Junior” host went on to say that she gained 70 and 55 pounds while carrying her eldest two children.

“I went into hiding,” she recalled. “I always thought, you know, I’m going to have kids and go right back to work and pop back into shape and it’s not that easy.”

The “Sports Illustrated Swimsuit” model is believed to have welcomed River via surrogate, as she did not appear pregnant three months before the infant’s arrival.