- “Come little children, I'll take thee away
Into a land of enchantment
Come little children, the time's come to play
Here in my garden of magic.”
- ―Sarah's siren song to charm children
Sarah is extremely flirtatious and enjoys "playing" with people, men in particular. As she has a sadistic sense of humor, it is strongly implied that "playing" with people means torturing them or simply sleeping with them inappropriately. Even so, she is very obedient to her eldest sister Winifred and would unlikely be as evil as she is without her guidance. Although Sarah is an airhead (much to Winifred's frustration) and often says or does stupid things, her unique power -her enchanting, siren-like voice- can and has lured children to their doom. She can even charm all the children in Salem at once, making her a very powerful, dangerous, and valuable witch. She also has a one sided crush on Max.
Sarah is the most beautiful of the Sanderson Sisters with long, wavy blonde hair, fair skin, and a slender frame. She dresses in shades of purple including a bodice with flowery embroidery and lacy sleeves, a deep purple skirt over another, redder skirt with a slit up the side, and stockings with black boots. When outside or flying, she wears a purple cloak.
The Sanderson Sisters, now graying and stooped with age, send Sarah out to lure a child to their cottage so that they may steal its life force to restore their own youth and vitality via a special potion. With the entrancing power of her voice, Sarah lures a young girl named Emily Binx into their cottage in the woods. However, she is unaware that they were spotted by Emily's elder brother, Thackery, and that he is following them.
With a bewitched Emily docilely sitting in a chair, Sarah gleefully helps her two sisters, Winifred and Mary, with the potion. All three are downright giddy that their youth will be restored soon; Sarah even engages in a playful fight with Mary by throwing dead men's toes at each other. However, just after Emily obediently drinks the potion, Thackery interrupts them and attempts to rescue her. Sarah and Mary happily chase him around the room, but he manages to knock them down by shoving their enormous cauldron at them, spilling the rest of the potion in the process. A furious Winifred easily subdues him with her powers before Mary points out that the potion is working: Emily's life force is visible. The sisters eagerly crowd around Emily and suck her life force away until their youth is restored and Emily dies of old age.
Rejoicing at the success of their potion, the witches then turn their attention to Thackery. Sarah suggests that they hang him on a hook and let her play with him, but Winifred sharply rejects the idea. Initially planning to simply kill him, Winifred changes her mind when he calls her a hag and decides that he deserves a harsher punishment. Together with her sisters, she curses him to live forever in the form of a black cat, doomed to live for all eternity with the guilt of his failure to save Emily.
Just after they perform the spell, an angry mob arrives at their cottage, led by Emily and Thackery's parents. Winifred and Mary attempt to barricade the door and convince the crowd that they're merely spinsters spending a quiet evening at home, but air-headed Sarah impulsively adds that they've been killing children before her sisters can stop her. Soon enough, the sisters are captured and hanged. But before they die, Winifred casts one final spell declaring that on Halloween night when the moon is full, a virgin will summon them back from the dead, allowing them to once again claim the lives of all the children in Salem.
300 years later on Halloween night, a boy named Max Dennison takes his little sister Dani trick-or-treating. His crush, Allison, takes them to see the Sanderson cottage, which has been turned into a museum, as a special treat. They break in and Max foolishly lights the candle thinking that it's just a bunch of hocus pocus and ends up resurrecting the Sandersons. He steals Winifred's spellbook at the behest of Thackery so that the sisters cannot create the potion needed to steal the life force of children and they run.
The children all ran to the cemetery as Thackery led them however the sisters all followed them on their broomsticks and nearly got the book back. However, before they can escape Winifred raises Billy Butcherson, her former lover, back from the dead and instructs him to get the book back before flying away to the outside of the cemetery as they cannot set foot on hollowed ground. There they employ the help of a bus driver and ask him to find them children and eventually come across a house owned by a man dressed as the devil who they mistake for their master. They subsequently get into a fight with his wife as Sarah was dancing with him but are scared away by the dog. Outside they find that their broomsticks have been stolen.
The sisters then follow the children to the party where Max's parents are and after being exposed to the room by Max, Winifred takes charge and ridicules him before singing "I Put a Spell on You" therefore enchanting all the adults causing them to dance until they die. After this the children lead the sisters to the school after Allison gets an idea from a restaurant and after unwittingly walking into a kiln they are locked in and the children burn them alive.
However, they did not die due to the curse protecting them from death until sunrise and they end up capturing and locking up Jay and Ernie, the two bullies that make fun of Max after they call them ugly. Winifred, desperate for her eternal youth decides to try and make the potion from memory. Sarah, surprisingly, shouts out the correct ingredient but is hushed by Mary who thinks Winifred has all the right answers. At Max's house though he and Allison open the book therefore allowing it to send out a signal to the sisters who fly to the house, using a modern cleaning broom, mop, and vacuum cleaner as improvisations for their stolen broomsticks and take the book and kidnap Dani and Thackery. Sarah is instructed to sing her siren song to all the children of Salem so they will go to the house.
After brewing the potion again they try to get Dani to drink it but are stopped by Max who tricks them into thinking the sun has risen by using the headlights of his parents' car. However they realize they have been tricked and follow the children back to the cemetery and attempt to get Dani to drink the potion again though Winifred drops it whilst Sarah tries to help Mary escape the children. Max catches it and threatens to smash it though instead drinks it after Winifred says she'll kill Dani if he smashes it. After a struggle with him, they both fall to the ground and she starts to take his life force but the sun comes up. Winifred transforms into stone and explodes while her two sisters implode in purple and orange light.
At the end of the film, however, the book is seen and it blinks, therefore hinting the sisters may return once again.
Sarah and her sisters began appearing in a special Halloween themed Castle Show at Disney's Magic Kingdom in 2015 as a part of Mickey's Not-So-Scary Halloween Party. Sarah kicks off the festivities by sending out the call to fellow villains by singing "Come Little Children". After completing their potion, she and Mary back up Winifred as she sings "I Put a Spell on You" and dances with various villains.
- Sarah's siren song is an excerpt from Edgar Allan Poe's poem "Come Little Children". However, her version ends with the word "magic" whereas his ends with "shadows."
- One major element deleted from the film had the witches giving the children (and Emily Binx early on) drugged candy crows in order for Sarah's song to take effect. This was most likely removed due to the fact that candy crows were not invented until the 1880's and it would have been seen as illogical if Sarah could not enchant the children with "Come Little Children" on her own.
- She has the same name as her portrayer, Sarah Jessica Parker.
- In real life, Sarah Jessica Parker is a descendant of Esther Elwell, a woman who was put on trial for being a witch in Salem in the late 1600's. The witch craze ended only a month before her trial.