In 2011, Brewer made her television debut as Adelaide "Addie" Langdon in American Horror Story: Murder House.

Also in 2013, she returned to American Horror Story for the third season, subtitled Coven, playing the supporting role of Nan, a young witch who is clairvoyant.

It was announced at the 2014 PaleyFest that Brewer would return to the series for the fourth season, subtitled American Horror Story: Freak Show.

In February 2015, Brewer became the first woman with Down syndrome to walk the red carpet at New York Fashion Week, which she did for designer Carrie Hammer.

[14] The same month, during an interview, Brewer was asked if she would make an appearance in American Horror Story's upcoming fifth season, subtitled Hotel.

[14] In May 2017, Brewer starred in the comedy short Whitney's Wedding, in which she played a bride who gets 'cold-feet' when she starts thinking her fiancé is not "normal".

“I thought she would beautifully encompass the Happy Hippie Foundation and all we represent.”[16] Brewer also returned to American Horror Story on its seventh season Cult.

[18] In February 2018, Brewer made her off-Broadway debut in Amy and the Orphans, a play by Lindsey Ferrentino about three siblings, one of whom has Down Syndrome, in the wake of their father's death.

[19] In April, Brewer was nominated for an Outstanding Featured Actress in a Play by the Outer Critics Circle Awards for her performance in Amy and the Orphans.

[20][non-primary source needed] During October, Brewer briefly appeared on American Horror Story once again, on its eighth season subtitled Apocalypse, where she reprised the role she played in Coven.