He was a central figure in the Bedre-Byggeskik movement and succeeded Carl Petersen as a professor at the Royal Danish Academy of Fine Arts's School of Architecture in 1923.

He attended the Royal Danish Academy of Fine Arts from 1900 to 1902 but received most of his training as an architect, draughtsman, and pupil at Peder Vilhelm Jensen-Klint's practice.

[2] Bentsen was part of a circle of young architects and artists including Vilhelm Wanscher, Carl Petersen, Hans Koch, Povl Baumann, Thorkild Henningsen and Kaare Klint.

In 1920 Bentsen returned to Copenhagen to work at the Royal Danish Art Academy's School of Architecture, initially as Carl Petersen's assistant and then, from 1923, succeeding him as a professor.

He still focused on residential architecture in his private practice, ranging from single-family detached homes over terraced housing developments (Bakkehusene) to apartment buildings (Kastelshaven).