She grew up in Oregon and attended Valley Catholic from kindergarten to 12th grade, and the University of Notre Dame where she majored in anthropology.

[10] Zagunis was the first American fencer to hold the Jr. World Cup Champion title (2002), and she did so three years in a row (2002, 2003, 2004).

She was the first fencer in the history of the sport to hold more than two World Champion titles in one season (2001: Cadet, Jr. and Jr.

She repeated as World Champion one year later, again winning the individual sabre title, defeating the Ukraine's Olga Khomrova 15–11 in the final.

[13] Zagunis faced Chinese fencer Xue Tan in the finals, defeating her 15–9 and becoming the first American to win an Olympic fencing gold medal in 100 years.

Because fellow American Sada Jacobson had become the first U.S. woman to be ranked #1 in the world in women's sabre (in 2003), she was considered a favorite.

Zagunis then faced her training partner from the Oregon Fencing Alliance, Rebecca Ward, in the semifinals and defeated her 15–11.

In the gold medal match, Zagunis faced the other top seed in the tournament, Sada Jacobson, and won, 15–8.

[21] She jumped out to a 7 to 0 lead in her round of 32 match against Canadian Gabriella Page (seeded 23) and scored the last five touches to win 15–3.

[22] On March 3, 2017, Zagunis was announced as one of 16 celebrities participating in a cooking competition on the Food Network TV series Chopped.

[23] She was featured in the "Star Power: Culinary Muscle" episode, alongside former NFL player LaMarr Woodley, former gold medalist figure skater Dorothy Hamill, and current female UFC fighter Paige VanZant.