Following World War II and the denazification process he became Director of the Art Association for the Rhineland and Westphalia, until his death in a car accident at the age of 61.

The lack of artistic recognition and depression led to her suicide in 1919; Gurlitt took care of her works, but part of it was destroyed by their mother after the death of their father.

A collection of his letters shows that he was personally well acquainted with modern artists at the time, and he acquired and exhibited works by many of them, including Barlach, Feininger, Hofer, Kandinsky, Kirchner, Klee, Kokoschka, Lissitzky, Marc, and Munch.

[2][14][15] Following his dismissal Gurlitt moved to Hamburg, where he became the curator and managing director of the Kunstverein (Art Association) until he and the board members were forced to resign by the Nazis in 1933.

[16][17] From the mid 1930s onwards, Gurlitt purchased and, in some cases, onsold artworks, often bought for low prices, from private individuals, including Jewish owners who were under duress to pay extortionate taxes, or were otherwise liquidating assets in order to flee the country.

[2] Gurlitt's name appears against many of the entries on a listing compiled by the Ministry of Propaganda and now held by the Victoria and Albert Museum that provides details of the fate of each object, including whether it was exchanged, sold or destroyed.

[22] In early 1943, Hermann Voss, director of Hitler's planned Führermuseum in Linz, named Gurlitt his official purchasing agent.

Under interrogation after capture, Gurlitt and his wife told United States Army authorities that in the fire bombing of Dresden of February 1945 much of his collection and his documentation of art transactions had been destroyed at his home in Kaitzer Strasse.

Over the next five years he staged over 70 exhibitions of leading modern artists and brokered the sale of paintings with at least some of the proceeds going to the Association, while at the same time dealing privately and purchasing works for his own collection, including Courbet's Village Girl with Goat for which he paid the then very large sum of 480,000 French Francs.

Upon his death, he was celebrated in German newspaper articles and speeches for his championing of modern art and its creators, and even had a street named after him in Düsseldorf.

[31] However, the declassification of military and intelligence archives beginning in the late 1990s[32] and the discovery of a hoard of hidden artworks in the Munich home of his son[33] have led to a well-documented reappraisal.

For critic James McAuley, writing in "Even" magazine after viewing the two recent public exhibitions of selected works from the collection, Gurlitt was a morally bankrupt and "dreadfully mediocre art dealer whose animating principle seems to have been profit and professional advancement" who "made his career in the arts, but without any real distinction", "swindled them all" and went on to state: "The art in Bonn and Bern adds up to a collection of no particular distinction, larded with trite, second-tier works on paper by artists of middling distinction, and the real, unexpected achievement of 'Status Report' is that it exposes the truth about Hildebrand Gurlitt – his mediocrity, his uncomplicated interiority, his utter predictability",[37] although other commentators are much less dismissive about the collection's quality (see note).

[a] Writing in 2018, Rebecca O'Dwyer says: Hildebrand Gurlitt was a canny operator who, despite being part Jewish, managed not only to survive but to thrive in Nazi Germany.

[39]Author Catherine Hickley offered her own assessment of Gurlitt's actions in 2015: He was an anti-Nazi who became corrupted by the regime he professed to hate; whose fear and ambition combined led him to compromise his own beliefs and, in the process, forfeit his integrity.

[43] In 2007, August Macke's Woman with a Parrot, also with a Hildebrand Gurlitt provenance, was sold in Berlin via the auction house Villa Grisebach for €2 million;[44] the seller was an unnamed German collector, suspected by investigative author Catherine Hickley to have been Cornelius' sister Renate (Benita).

[45] On 22 September 2010, German customs officials at the German–Switzerland border found Cornelius, by then aged 77, to be carrying €9,000 in cash which he explained was money from the previous sale of a painting, which led to a search warrant in 2011 for his apartment in Schwabing, Munich.