She is best known for her roles in the television series Reply 1988 (2015–2016), Avengers Social Club (2017), and The Good Bad Mother (2023), as well as the films Ode to My Father (2014), The Himalayas (2015), The Last Princess (2016), Miss & Mrs.

Before making her film debut in Lady Vengeance (2005), Ra Mi-ran spent years acting in theatre.

Afterwards, she appeared in more than 40 films but did not receive acclaim or public recognition until she starred in Dancing Queen (2012), with one review calling her "the standout" as the protagonist's best friend and hairdresser.

[9][10] Ra was also praised in her leading role as a North Korean defector in Jeon Kyu-hwan's indie 'Dance Town' (2011), with Variety calling it "riveting" and "a landmark performance."

Through the reality show Sister's Slam Dunk, she along with cast members Min Hyo Rin, Kim Sook, Hong Jin Kyung, Jessi, and Tiffany debuted as a girl group with the oldest average age in K-pop history, under the name 'Unnies'.