She was a close collaborator with Ludwig Mies van der Rohe for more than ten years during the Weimar period from 1925 until his emigration to the U.S. in 1938.

Her fame was posthumous, as the significance of her contribution to the work of Mies van der Rohe and others with whom she collaborated only became clear through the research of later historians of the field.

First, she designed well-received interiors for a worker's apartment and two stores for the Lyzeum-Klub exhibition Die Frau in Haus und Beruf (Woman at Home and at Work).

[7] The first exhibition, entitled "The Applied Arts," consisted entirely of women's clothing and accessories, seeking to promote the revival of German fashion and increase cooperation between artists and manufacturers.

The second exhibition was an enormous undertaking with the display of more than 1,600 objects, many chosen by Reich, to showcase the quality and breadth of German industrial design.

In 1929 she became the artistic director for the German contribution to the Barcelona World Exposition, where van der Rohe designed his world-famous pavilion.

Her tenure was short-lived as the Bauhaus was closed in 1933 by the Nazis, who referred to it as an "oriental palace" and "synagogue" filled with "Bolshevists" and "cultural Marxists" dedicated to degenerate art.

Through her involvement with the Werkbund, Reich met Ludwig Mies van der Rohe and moved from Frankfurt to Berlin to work with him in 1926.

It is said[citation needed] that they were constant companions, working together on curating and implementing exhibitions for the Werkbund, as well as designing modern furniture as part of larger architectural commissions, such as the Barcelona Pavilion in 1929 and the Tugendhat House in Brno.

[citation needed] Albert Pfeiffer, Vice President of Design and Management at Knoll, has been researching and lecturing on Reich for some time.

He points out that:[14] It became more than a coincidence that Mies's involvement and success in exhibition design began at the same time as his personal relationship with Reich...

[13] The Barcelona Pavilion is considered to be a masterpiece of modern design, however, Lilly Reich is rarely mentioned in textbooks, nor given proper credit for her contributions.

[18] In 2018, the Mies van der Rohe Foundation in Spain presented the first edition of the Lilly Reich Grant for equality in architecture.

The grant was specifically addressed to the study of the work by Lilly Reich herself, and to delving into the knowledge and dissemination of an essential figure in the history of modern architecture.