Seymour has heterochromia: where her right eye is hazel and her left is green. In 2007, she admitted to having undergone plastic surgery, including breast augmentation and eye lift.

Seymour has been married four times, and has four children:

In 1984, Seymour bought with then-husband David Flynn the Grade One listed St Catherine's Court for £350,000, located in the village of St Catherine, near Bath, Somerset. After spending £3 million on refurbishments, she spent her summers at the house and her winters in Malibu. After her divorce from Flynn and marriage to Keach, she spent more time in America, and made little use of the house, so she began to rent it out. In 1994, during that season's filming for Dr. Quinn, Medicine Woman, she rented it to English rock group Radiohead, who recorded their album OK Computer at the house. In May 2007, she was granted a 24-hour alcohol and entertainment licence under new UK regulations. However, this caused much disturbance with neighbo