Dan Băjenaru received his initial training at the School of Fine Arts in Bucharest under G. D. Mirea, a central figure of Romanian academic painting, and Costin Petrescu. From 1927 he continued his studies in Paris at the Académie Julian and the Académie Ranson, and as a scholarship holder of the Ministry of Cults and Arts attended the Romanian School at Fontenay-aux-Roses. His formation was equally shaped by repeated stays at Baia Mare, where he worked as a scholar during the summers between 1919 and 1926, absorbing the plein-air and naturalist principles of the colony.

His exhibition debut took place in Paris in 1926 with a solo show, followed by participation in the Salon d'Automne in 1927. The international dimension of his career was consolidated with a silver medal at the Paris Universal Exhibition of 1937. From 1929, he was a regular presence at the Official Salon in Romania, where his work received multiple distinctions, and between 1930 and 1940 he exhibited with Tinerimea Artistică and Grupul Nostru. He also showed in solo exhibitions in Bucharest, Bacău, Ciudad de Mexico, New York, and Los Angeles, and his work featured in itinerant exhibitions of Romanian art across major European cities. A retrospective was organized in Bucharest in 1975.

His landscape painting is characterized by a controlled brushwork that introduces subtle visual inflections within classical compositional structures, resisting the singularity of strict linear perspective. The breadth of his thematic range extended to portraiture and historical composition, including works connected to his family background: his father, Ion Băjenaru, was a tenor and one of the founders of Romanian Opera, immortalized by the artist in the painting Inițiatorii operei române.

His career unfolded across the interwar period and into the communist era, a trajectory that, as with many Romanian artists of his generation, involved navigating the ideological demands of Socialist Realism alongside a more personal pictorial practice.