She is best known for her work as editor on her husband George Miller's films, including Babe: Pig in the City (1998), Happy Feet (2006), and Mad Max: Fury Road (2015).

[1] In 1984, Sixel began work as an assistant editor and dubber on the Australian television mini-series, The Last Bastion (1984), where she met one of the directors of the picture, and future collaborator, George Miller.

[citation needed] Margaret Sixel has creatively contributed to the production of numerous projects throughout her career, including Babe (1995), in which George Miller credits her for turning the picture around by "declaring an early cut [of the film] too episodic and lacking in narrative tension, and suggesting the linking devices of chapter headings and singing mice.

"[4] She has stated that being his spouse only helps in that they understand each other's sensibilities better, since "98 percent of the time [they] agree on [their] choices," which is important, "because when you are not in sync, lots of people have opinions in the editing room and you can really go off in the wrong direction.

"[6] Because the majority of the film revolves around an intense road battle, featuring dozens of vehicular stunts and hundreds of individual extras, the location team would shoot with upwards of 20 cameras on any given set up.

[5] Throughout her career working with Miller, Jason Ballantine was her first assistant and additional editor on every feature film from Babe: Pig in the City to Mad Max: Fury Road.