The 34-year-old Season 4 winner announced on social media that wife and "The Bachelor" Season 13 contestant Ann Lueders gave birth to son Carter James on Tuesday.
"Well Carter James Csincsak is finally here!!!" he tweeted before adding, "Pretty excited to get to share #carterjamescsincsak with the world today!!" on Instagram.
Csincsak and Lueders are also parents to 5-year-old son Noah and 2-year-old daughter Charlotte.
The couple told People they named their youngest after Lueders' late father, Brian Carter Lueders.
"My father-in-law Brian Carter Lueders was a huge part of our lives. Not only was he a grandfather [and] father, but he was a part of our daily routines," Csincsak said. "He was always there when we needed help for something."
"He always had a smile on his face, and I never once heard him complain! If Carter has just half the amazing traits my father-in-law did, he will turn out to be an amazing man. He was one of the greatest men I have ever had the chance to know personally, and he is dearly missed," he added.
Csincsak also revealed that Noah and Charlotte are thrilled to have a new sibling. He described his elder kids' interactions with the baby as "heartwarming," saying Noah will be "a great big brother."
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"Our oldest, Noah, is such the protector of Carter already," the star said. "And Charlotte is like a second mother."
Csincsak and Lueders married in 2010 after meeting at a "Bachelor" reunion party.
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