From 1905 Mackowsky wrote for the art magazine Kunst und Künstler published by Bruno Cassirer.

From 1908 he was a lecturer at the Humboldt-Akademie (Humboldt Academy), and the privately run Lessing-Hochschule (Lessing University) in Berlin.

Mackowsky made a name for himself as the author and editor of books on important artists from the 18th to the 20th century, and as a museum guide.

Karl Scheffler wrote about Mackowsky in his memoirs[2] in 1946:He was the best connoisseur of old Berlin, but because of all his studies, it was not easy for him to write.

For years he could hunt for a single historical fact that he still lacked; he preferred to leave almost finished works lying around than to publish them without final nuances.