Kim Zolciak’s oldest son, KJ Biermann, with former NFL player Kroy Biermann, has grown up largely in the public eye, first appearing as a baby on The Real Housewives of Atlanta and later on the family’s spin-off Don’t Be Tardy. Fans who followed the household through reality television often wonder about the ages of the younger Biermann children as they move from childhood into their teenage years.
As of August 2026, KJ Biermann is 15 years old. Born Kroy Jagger Biermann on May 31, 2011, in Atlanta, Georgia, he celebrated his 15th birthday earlier this year. His mother has publicly marked the occasion with affectionate messages, describing him as a source of joy, laughter, and pride while noting how quickly time has passed.
Family Background and Early Life
KJ is the first biological child of Kim Zolciak and Kroy Biermann, who married in November 2011. The couple later welcomed son Kash in 2012 and twins Kaia and Kane in 2013. Kroy also legally adopted Kim’s older daughters, Brielle and Ariana, creating a blended family of six children.
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Viewers of the Bravo series watched KJ from infancy through his early years as the family balanced everyday parenting with the demands of reality television. He was frequently portrayed as energetic and humorous, the “funniest and most rambunctious” of the siblings according to longtime observers.
In more recent years, KJ has focused on high school athletics, following in his father’s footsteps as a football player. He has been noted for his size and commitment to the sport, standing well over six feet tall while still a teenager. Kim has shared updates highlighting his dedication to training, school, and the game.
Current Age and Public Interest
With a birth date of May 31, 2011, KJ turned 15 in the spring of 2026 and remains that age through the current summer months. Public curiosity about him often arises alongside interest in the larger Biermann family, especially as the older children pursue independent paths and the younger ones continue growing. While the family has experienced personal changes in recent years, including the parents’ separation, KJ’s place as the eldest son remains a straightforward fact grounded in widely reported biographical details.
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In short, Kim Zolciak’s son KJ Biermann is 15 years old as of August 2026.
