In 1831 he was appointed director of the Zoological Department at the St Petersburg Academy of Sciences, where he published in Russian. Brandt encouraged the collection of native animals, many of which were not represented in the museum. Many specimens began to arrive from the expeditions of Severtzov, Przhevalsky, Middendorff, Schrenck and Gustav Radde.
He described several birds collected by Russian explorers off the Pacific Coast of North America, including Brandt's cormorant, red-legged kittiwake and spectacled eider. He is also commemorated in Brandt's bat, Brandt's hedgehog, three other species of mammals, and the lizard Iranolacerta brandtii. Brandt was also an entomologist, specialising in Coleoptera (beetles) and Diplopoda (millipedes).
He died in Merreküll, Estonia. Acipenser baerii Brandt, 1869 (Siberian sturgeon)
Acipenser guldenstadti Brandt & Ratzeburg, 1833 (Caspian or Russian sturgeon)
Acipenser schrenckii Brandt, 1869 (Amur sturgeon)
Emberiza bruniceps Brandt, 1841 (Red-headed bunting)
Emberiza cioides Brandt, 1843 (Meadow bunting)
Holothuria leucospilota Brandt, 1835 (black long sea cucumber)
Idotea ochotensis Brandt, 1851
Lasiopodomys brandtii (Radde, 1861) (Brandt's vole)
Ligia dilatata Brandt, 1833 (sea slater)
Mesocricetus brandti (Nehring, 1898) (Brandt's or Turkish hamster)
Myotis brandtii Eversmann, 1845 (Brandt's bat)
Paraechinus hypomelas (Brandt, 1836) (Brandt's hedgehog)
Phalacrocorax penicillatus (Brandt, 1837) (Brandt's cormorant)
Somateria fischeri Brandt, 1847 (spectacled eider)
Stichopus chloronotus Brandt, 1835 (black sea cucumber)
Trionyx maackii Brandt, 1858 (Chinese softshell turtle).
German Academy of Sciences Leopoldina. Russian Academy of Sciences. Russian Academy of Sciences.
French Academy of Sciences.