Born at Cassel, he began his art education in 1827 in Düsseldorf under Friedrich Wilhelm Schadow at the Düsseldorf Academy of Painting. In his early work he followed the pseudo-idealism of the German romantic school, but on removing to Munich in 1835, the stronger influence of Louis Gurlitt turned his talent into new channels, and he became the founder of the German realistic school. Although his landscapes evince too much of his aim at picture-making and lack personal temperament, he is a master of technique, and is historically important as a reformer.

A number of his finest works are to be found at the Berlin National Gallery, the New Pinakothek in Munich, and the galleries at Dresden, Darmstadt, Cologne, Düsseldorf, Leipzig and Hamburg.

He died in Düsseldorf.

His brother, Oswald Achenbach (1827-1905), was also a painter.