Big was born on January 6, 1970 in La Jolla, California, and spent her early years living on St. Thomas in the Virgin Islands. By the age of 7, she had already reached five feet in height. After relocating to St. Petersburg, Florida, Gabby began playing volleyball at the high school level. She earned an athletics scholarship to Florida State University in 1987, and majored in Communications.

Reece competed in volleyball as a Lady Seminole from 1987 to 1990, where she set season records for solo and total blocks, and earned several All-Tournament honors. In her junior year, Reece was named Most Inspiring Collegiate Athlete in the country, and was inducted into Florida State's Athletic Hall of Fame.

In early 1989, Reece began modeling for the Ford Agency of New York, and before year's end, was selected by Elle magazine as one of the five most beautiful women in the world. She would go on to grace the covers of magazines such as Harper's Bazaar, LIFE and Women's Sports & Fitness, though volleyball always took precedence over everything else, no matter how lucrative.

In 1993, Reece became Nike's first ever female cross-training spokesperson, appearing alongside Bo Jackson in TV ads. That same year, she began competing in the four-person Bud Light Pro Beach Volleyball League, leading in blocks during her first season, and kills her first four. She became captain of team Nike in 1994, and was named the League's Offensive Player of the Year for two consecutive seasons.

Reece hosted segments of MTV Sports from 1993-1996, as well as The Extremists (1995), where she got to try her hand at a variety of high energy activities including drag racing, white-water kayaking, and skydiving. From 1994 through '95, she wrote a sports and fitness column for Elle magazine. Following her fifth and final season with the Bud Light League in 1997, she co-authored Big Girl in the Middle with Karen Karbo, which chronicles her triumphs and defeats as a top female pro athlete. She made a cameo appearance as a fitness trainer in Gattaca (1997), and began contributing a regular column to Women's Sports & Fitness. That November, she married extreme surfer Laird Hamilton.

She switched to competing in the two-person Federation of International Volleyball circuit in 1999, and posted back-to-back thirds with partner Holly McPeak during their first season together. In 2000, 6'3" Reece graced the cover and interior pages of Play..boy.

Reece has recently been working on improving her golf swing, and trained with coach Claude Harmon in the hopes of eventually qualifying for the LPGA. She became the first woman to compete at the American Century Pro Celebrity Golf Tournament in 2002. She landed another career as a reporter in November, covering golf for USA Sports, including the 2003 PGA Tour.