Ana de Mier y Ortuño was born on 12 April 1981 in Granada, Spain to a Spanish mother and a Colombian-German father. At the age of five, she moved with her parents to her paternal grandmother's hometown, Munich, where she went to school. As a teenager, her great passion was dance, which made her neglect school. She completed her A-levels by training as a foreign language correspondent for English and Spanish, followed by a vocational secondary school. According to her own statement, Mier y Ortuño did not have any concrete career aspirations at that time and so, inspired by her Spanish grandfather, an architect, she initially began to study architecture. In 2007, she spontaneously accepted an internship with film editor Alexander Berner, who was working on "Der Baader Meinhof Komplex" ("The Baader Meinhof Complex") at the time and who, after the premature departure of his assistant, made her his new assistant. She subsequently worked as an assistant editor on other feature films, including the German-American documentary "Jane's Journey" and the historical drama "Henri 4", both of which were released in 2010. She also worked on the international 3-D action films "The Three Musketeers" (2010) and "47 Ronin" (2013) as assistant stereographer.  

Ana de Mier y Ortuño has been working as a freelance film editor since 2014, editing comedies such as "Abschussfahrt" (2014) and "Bruder vor Luder" (2015) as well as children's and youth films such as "Die Vampirschwestern 3" ("Vampire Sisters 3 – Journey to Transylvania", 2016) and "Jim Knopf und Lukas der Lokomotivführer" ("Jim Button and Luke the Engine Driver", 2018, co-edited with Ueli Christen).

She was nominated for the German Film Award 2019 for her work on the Cyrano de Bergerac-inspired, youthful romantic comedy "Das schönste Mädchen der Welt" ("The Most Beautiful Girl in the World"), directed by Aron Lehmann.

Immediately after finishing her work for this film, she edited Florian David Fitz's social comedy "100 Dinge" ("100 Things"), about two friends who, faced with their own consumerism, lock up all their possessions and are allowed to retrieve only one item per day for 100 days. In 2019, the children's film "Benjamin Blümchen - Der Kinofilm" ("Benjamin the Elephant", 2017), shot entirely in front of a green screen, and the adaptation of Bov Bjerg's bestselling novel "Auerhaus" (directed by Neele Leana Vollmar), set in the 1980s, were released.    

Afterwards, Ana de Mier y Ortuño worked, among other things, as an editor for the German Netflix series "Das letzte Wort" ("The Last Word", 2020), in which the main character, portrayed by Anke Engelke, trains to become a funeral orator after the sudden death of her husband.   

In 2020 she took on the editing of Hüseyin Tabak's transgender story "Oskar's Kleid", penned by and starring Florian David Fitz. The cinema release is planned for October 2021.