Oz, the eldest child of popular television Doctor Mehmet Oz and Lisa Oz, was born in Philadelphia, Pennsylvania. She was born with the umbilical cord wrapped around her neck and was given an Apgar score of 2, but made a full recovery. Her paternal grandparents, Suna (née Atabay) and Mustafa Öz, emigrated from Konya Province, Turkey. She also has Shapsug ancestry from her maternal great-grandparents. She was raised in Cliffside Park, New Jersey, where she graduated from Dwight-Englewood School in 2004. She has three siblings, Arabella, Zoe and Oliver. Oz graduated with a degree in Near Eastern Studies from Princeton University in 2008.

Oz's first book, The Dorm Room Diet (Newmarket Press, 2006), advanced her approach to avoiding the "Freshman 15". The book covers her advice on how to develop healthy habits while in college that may benefit the student through life. The book was publicized by multiple media outlets including The New York Times,The Wall Street Journal,People, The Washington Post,Reader's Digest, Teen Vogue, Cosmo Girl! and Seventeen. She made promotional appearances on Good Morning America, Fox & Friends, The Nate Berkus Show, The Tyra Banks Show, NPR Weekend Edition, and her father's program, The Dr. Oz Show.

In 2007, she published The Dorm Room Diet Planner (Newmarket Press, 2007). In 2012, she collaborated with the rest of the cast of The Chew to author The Chew: Food. Life. Fun. Oz also is the author of the New York Times bestselling Relish: An Adventure in Food, Style, and Everyday Fun. The book contains recipes, tips, relationship and career advice, and the author's personal anecdotes. Oz has written articles for Glamour and The Huffington Post. In 2012, she wrote five articles for a column called "Food for Thought" for Creators Syndicate.

Oz speaks publicly on lifestyle and health topics. In 2008, she was invited to speak at The Governor's Women's Conference, hosted by Maria Shriver. Oz was a featured speaker at The Aspen Institute's 2009 Aspen Health Forum. In 2011, Oz and her mother Lisa were the featured speakers at WCBS Radio's Working Women's Luncheon. Daphne Oz has delivered addresses to campus audiences including Princeton University, University of Pennsylvania, Brown University, and Georgetown University.

On August 26, 2010, Oz married John Jovanovic at the Municipal Marriage Bureau in Manhattan. Jovanovic is an investment fund analyst, whom Oz met in college. The civil ceremony was followed by two religious ceremonies on August 28, 2010. A morning ceremony was held at the Synaxis of Serbian Saints Church in Portland, Maine. A second ceremony was held in the evening at the summer home of Oz's maternal grandparents, Gerald and Emily Jane Lemole, in Cumberland Foreside, Maine. The ceremony was led by the Rev. Prescott Rogers of the Swedenborgian Church.

On February 26, 2014, Oz gave birth to a daughter, named Philomena "Philo" Bijou Jovanovic. Her father described the baby as being a blue-eyed Circassian beauty, just like her mother. Daphne gave birth to a son, Jovan Jr. – nicknamed "John-John" – on October 21, 2015. On June 6, 2017, Oz announced on The Chew that she was expecting her third child the following winter. On December 4, 2017, Oz gave birth to a daughter, Domenica Celine Jovanovic.

Oz was one of five co-hosts on ABC's The Chew, a weekday one-hour lifestyle show, which premiered in September 2011. On August 11, 2017, it was confirmed that Oz would be leaving the show prior to the release of the seventh season. Oz has been featured as a guest co-host on The View,"Beat Bobby Flay", and has appeared as a healthy living expert on Good Morning America, Fox & Friends, The Dr. Oz Show, The Rachael Ray Show, Dayside, and Good Day New York. She was also one of the Celebrity guests on the game-show Celebrity Name Game. Oz is currently a judge on the Food Network competition show Cooks vs. Cons.