The Witch lives the life of a wood carver, and uses her knowledge in magic to help her in her work. The Will O' the Wisps lead Princess Merida to her hut, and the woman insists in presenting herself as a simple wood carver. But Merida rapidly realizes her real nature, after seeing a broom moving by itself, a speaking crow, and other abnormal wonders. The witch tells her that she's not a witch due to too many unsatisfied customers and tries get rid of Merida with floating knives until Merida offers to buy all of her carvings. In exchange of buying her entire stock, Merida convinces the witch to give her a spell in the form of a cake, to change her mother. Just as Merida leaves with the cake, the witch realizes she forgot something very critical about the spell but is too late to tell Merida.
When Merida comes back to the witch's hut, hoping to find a remedy to the spell, she finds, instead of the witch gone for the Wicker Man Festival in Stornoway, a potion-powered automated message through which the witch reveals the spell will become permanent by the second sunrise. The witch also leaves Merida a riddle: "Fate be changed, look inside, mend the bond torn by pride," which contains the way to revert the spell. The message repeats the phrase once more before disappearing. Merida begins to panic, as she doesn't understand the message, and tries to get the witch to appear again by pouring other vials of potions into the automated message, which causes it to become jumbled until the message explodes, completely destroying the witches cottage. She isn't seen again afterwards.
The Witch tells the legend of the eldest prince of the forgotten kingdom who sought her out to give a spell that will give him the strength of ten men and that would change his fate in exchange for his ring. So she does so and he became Mor'du and the kingdom crumbled into darkness and endlessly wandered. It was revealed the Witch was telling the story to Wee Dingwall who came to the witch. She offered him a spell to challenge his fate but he frightenly claimed that he just wanted a drink of water and tries to run out the door. The Witch kindly tells him to pull the door and then Wee Dingwall runs away screaming after thanking her politely. She says goodbye and closes the door to return to woodcarving.
Some time after the events of Brave, King Fergus visits the Witch, and asks for a magic object to help his army win the battle against the southern invaders. She gives him a magic helmet that will take away the fear of the soldiers. He tells her to collect the payment when the war is over. Later, Red Riding Hood comes to the witch, wanting to find people to be with, and the witch forces her to take her wolf form permanently and live with her as a guard dog. Later, she interrupts the coronation of Merida as queen of DunBroch to demand the payment that Fergus owed her before he died. She request she get either the enchanted helmet she gave him or a gigantic amount of gold, neither of with the people of DunBroch have. The witch demands the payment by the second sunset, and if it is not paid by then, she will cast the spell of Mor'du on the entire kingdom, prompting Merida to go on a quest to retrieve the helmet from the man who killed her father. Later, King Arthur and Zelena, the Wicked Witch of the West, enter her cottage. Her guard dog tries to attack them, but Zelena throws a temporary sleeping curse onto it. They tell the witch they want the helmet so as to make Arthur's army obey every command without question. She tries to bargain with them, but Zelena teleports behind her and grabs her, threatening to dunk her head in her own cauldron unless she tells them where it is. She quickly complies, telling them it is in the sea beside the forest. Later, Mulan goes to the witch to try to get a way to make Merida stand up for her kingdom, but the guard dog attacks her. Mulan spills a potion on the dog and turns it back into Ruby. They find Merida and the three defeat Arthur and Zelena. The witch tells Merida that she does not want the helmet, but was merely testing her to see if she would do what it took to rule the kingdom. She gives Merida an enchanted ale that will let her talk to her father's spirit.
In the original script of Brave, the witch was not present.
All of her carvings are bear themed, so it is possible that her magic is also bear themed, since both Mor'du and Elinor both became bears from it.
The Witch's real name is never given.
She is a woodcarver by profession, although she doesn't appear to be very good at keeping her secret, she very nearly gave it away to Merida thrice (the broom, the crow, and her near slip-of-the-tongue) before Merida realized it for herself.
There is an easter egg inside her cottage which is a picture of Sulley.
The Witch forgetting to disenchant her broom is the same mistake Merryweather made in Sleeping Beauty but the latter prevented hers from being seen by the princess of the movie.
She is referred to as the Witch Carver by some fans to distinguish her from other witches and because of her carving occupation.