Susan Sizemore began writing her own stories as a child. As an adult, she wrote fanfiction set in the Star Trek universe. She later began writing original romance novels. In 1991, when she was about 40, she won the Romance Writers of America Golden Heart Award, presented to a previously unpublished author. Three days later, she sold her debut novel, a time-travel romance called Wings of the Storm. Within several years, she was able to begin writing full-time.

Later in her career, she was asked to write a media tie-in novel based on the television series Forever Knight. Her book, Forever Knight: A Stirring of Dust, marked the first time she had written about vampires. This endeavor inspired her to create her own original series about a vampire world. The resulting series, known as Laws of the Blood, is a fantasy series with some romantic elements. Sizemore later created a second vampire world. Books in the new series, Primes, are paranormal romances, focusing much more on the relationships than the fantasy world. Although both series focus on vampires, Sizemore has created distinct and separate universes. Her background in cultural anthropology has helped her to create unique cultures for her vampires. Sizemore gives her vampires modern human problems, as they struggle with relationships and raising children. Each novel also prominently features a human character, allowing the books to show several very different perspectives on the worlds.

Sizemore has been nominated for two Romantic Times awards.

Laws of the Blood

• The Hunt
• Partners
• Companions
• Deceptions
• Heroes

Vampire Romance

• I Burn For You
• I Thirst for You
• A Touch of Harry in the Shadows of Christmas Past
• I Hunger for You
• Master of Darkness
• Primal Heat
• Primal Desires
• Primal Needs
• Dark Stranger

Time Travel Romance

• Wings of The Storm
• After the Storm
• The Autumn Lord
• In My Dreams
• One of These Nights
• My One True Love

Historical Romance

• Nothing Else Matters
• Scandalous Miranda
• Captured Innocence
• Too Wicked to Marry
• The Price of Passion
• On A Long Ago Night
• The Price of Innocence
• My First Duchess

Contemporary Romance

• Stranger by Her Side
• His Last Best Hope

Science Fiction

• Walking on the Moon
• Moons' Dreaming (with Marguerite Krause)
• Moons' Dancing (with Marguerite Krause)
• Forever Knight: A Stirring of the Dust
• Gates of Hell

Anthologies

• "Me, Myself, and Ay", in Time After Time
• "You Can't Go Home Again, Damn It! Even If Your Planet Hasn't Been Blown Up By The Vogons", in The Anthology at the End of the Universe: Leading Science Fiction Authors on Douglas Adams' The Hitchhiker's Guide to the Galaxy
• "Dish of the Day", in You Bet Your Planet
• "Among the Stars", in Rotten Relations
• "Every Little Thing She Does", in The Magic Shop
• "That God Won't Hunt", in Pharaoh Fantastic
• "Sometimes It's Sweet", in Vengeance Fantastic
• "Goodness Had Nothing to Do With It" in Familiars"
• "Rognarok Can Wait" in Heaven and Hell"
• "Coming to America" in Creature Fantastic
• "Dizzy and the Biker" in Murder Most Romantic: Passionate Tales of Life and Death"
• "I'm Not Making This Up" in Guardian Angels : Heart-Warming Stories of Divine Influence and Protection
• "A Butterfly Dreaming" in Perchance to Dream
• "One Riot, One Ranger" in Tall, Dark, and Dangerous
• "A Little Death" in A Dangerous Magic