After graduation, Dimitrescu painted murals for the Orthodox churches in Agăș and Asău (Bacău County).

[4] In 1917, along with the painters Camil Ressu, Iosif Iser, Marius Bunescu and the sculptors Dimitrie Paciurea, Cornel Medrea, Ion Jalea and Oscar Han, he founded the Art of Romania association in their Iași refuge.

In 1926, Dimitrescu, with Oscar Han, Francisc Șirato, and Nicolae Tonitza, established Grupul celor patru ("The Group of Four").

[5] He became a teacher at the Iași National School of Fine Arts in 1927, and, during the next year, he was named its headmaster (a position he held until his death).

Towards the end of his life, Dimitrescu began expanding his palette to cover more somber colors, while exploring compositions in which the background was stripped of details and usually of a dominant white.