He was an important art collector and patron in Prague; his collection contained Italian Renaissance paintings and early Baroque (Slavicek 1996, p.77); in the 1670s he purchased Netherlandish paintings in the Vienna shop of the art dealer Gulliermo Forchondt from Antwerp (Slavicek 1996, p.77). He built the baroque Palace Czernin one of the largest baroque buildings in Prague, it was finished after his death. The Czernin Palace was orginally meant for his large art collection of 750 paintings that he collected during his time in Venice and after. During his time in Venice he and his wife Maria Diana da Gonzoldo and his steward Filippo Leoncelli were very much involved with their art patronage and gave detailed directions to artists about the content of the desired paintings. Sometimes the Count commissioned different artists to paint the same subject at the same time (Turner et al 2006, p. 427). The collection reached a total of 1100 artworks in 1733. Later on the collection was sold and in 1778 dissolved. In 1668 he commissioned an inventory ('Imagines Galeriae') of his picture gallery by his court painters Jan la Fresnoy, Jakub van der Heyden, Folprechtus van Oude-Allen and Jasper de Payn, this special kind of inventory contains three volumes with 750 drawings (pen and wash) after the paintings (Slavicek 1996, p. 80-81). Czernin employed the Dutch painter Folpert van Alten-Allen (Ouden Allen) (1635-1715) as court painter (Fornasiero 2011, p. 120); Dutch painters Jakub van der Heyden were also employed on the Czernin estates (Mzykova 2012, p. 16)

Czernin bought paintings from Forchondt