[3] She has appeared on catwalks at the New York, London, Paris, and Milan fashion weeks, and has modeled for brands such as Chanel, Dolce & Gabbana, Fendi, Stella McCartney, and Versace.

[6][8][9] In September 2017, as one of the top models at Milan Fashion Week, she gained international attention when she posted a photograph of herself on Instagram wearing a t-shirt that said, "Bee Kind, I Have Autism".

[9] Marker was subsequently featured in the American edition of Vogue magazine,[3] and has since spoken regularly about mental health issues, sharing her frustration in school, which she says was ill-equipped to deal with her condition.

[5][9] In 2021, she told Vogue Business that she constantly needs to remind people how her neurodivergence affects her on set, where there are many stimuli that could lead to sensory overload, because of misconceptions that her "normal" appearance means she is neurotypical.

[10] She works with her agents at The Society and Elite to ensure that she has breaks between jobs to allow her to decompress, and that her travel plans are arranged to minimize stress and avoid possible triggers.