Wiggs began writing as a child, finishing her first novel, A Book About Some Bad Kids, when she was eight. She temporarily abandoned her dream of being a novelist after graduating from Harvard University, instead becoming a math teacher. She continued to read, especially reveling in romance novels. After running out of reading material one evening in 1983, she began writing again, using the working title A Book About Some Bad Adults.
For three years Wiggs continued to write, and in 1987 Zebra Books published her first novel, a Western historical romance named Texas Wildflower. Her subsequent historical and contemporary romances have been set in a wide range of settings and time periods. Many of her novels are set in areas where she's lived or visited. She gave up teaching in 1992 to write full-time, and has since completed an average of two books per year.
In 2000, Wiggs began writing single-title women's fiction stories in addition to historical romance novels. The first, The You I Never Knew, was published in 2001. After writing mass-market original novels for several years, Wiggs made her hardcover debut in 2003 with Home Before Dark.
Many of her novels are connected, allowing Wiggs to revisit established characters.
Her books have been published in many languages, including French, German, Latvian, Japanese and Russian.
Wiggs's books are frequently named finalists for the RITA Award, the highest honor given in the genre. She received the Romance Writers of America RITA Award for Best Romance of the year in 1993 for Lord of the Night. She won a second RITA in 2000 when The Charm School was named "Favorite Book of the Year." She has also won the RITA in 2001 for Best Short Historical for The Mistress. and in 2006 for Lakeside Cottage. She has also been the recipient of the Holt Medallion, the Colorado Award of Excellnce, and the Peninsula Romance Writer's of America Blue Boa Award. Romantic Times has twice named her a Career Achievement Award winner.