"Mirka and I are so incredibly happy to share that Leo and Lenny were born this evening! #TwinsAgain," Federer, who already has four-year-old twin girls, Myla Rose and Charlene Riva, wrote on his Twitter feed.
The Swiss great announced earlier Tuesday that he had withdrawn from this week's Madrid Open Masters 1000 event to be at the delivery. He's a three-time champion in Madrid.
"I've decided to withdraw from Madrid to be with my wife Mirka during these next few exciting weeks for our family," the 32-year-old Federer wrote on his Facebook page earlier in the day. "I'll be training near my home, and am excited to rejoin the Tour soon."