Initially aspiring to be a fashion journalist, her career took off at 17 years-old when she booked her first catwalk show with Marc Jacobs, becoming one of his favourites. She gained further recognition in 2011 on Channel 4's The Model Agency and has since walked for major brands like Giorgio Armani, Burberry, Tom Ford and Calvin Klein.
In 2017, she became a face of Rihanna’s Fenty Beauty. Anderson also worked with Pat McGrath, Uniqlo, Topshop, and Jones New York. After three castings, she debuted in the Victoria's Secret Fashion Show in 2015 and walked for four consecutive years. In 2019, she became the first British Black model to be named a Victoria's Secret Angel.
In 2016, Anderson launched LAPP Magazine to raise awareness about women’s mental health and empowerment, supported by her clothing brand, LAPP The Brand. As a women’s rights activist, she has delivered TEDx Talks, spoken at Oxford and Cambridge, and addressed racial discrimination in the modeling industry. In 2021, she launched the podcast Role Model with Leomie Anderson, and in 2023, she became the presenter of BBC’s Glow Up: Britain's Next Make-Up Star.