The project has seen the installation of 48 new displays in 24 state-of-the-art showcases themed around biodiversity, ecosystems, evolution, and Earth.
The museum said that together, the exhibits “encompass the intricate relationships between our planet and life”.
Thousands of specimens have been staged “in a fresh, bold design” within the main court and unique Victorian building.
The Megalosaurus, whose name means “great lizard”, is recognised as kick-starting the study of what would collectively become known as dinosaurs.
University of Oxford Prof William Buckland presented its fossilised remains to the Geological Society of London in 1824.
The remains, which measure nine metres in length and weigh about a tonne, will form part of the new prehistoric ecosystems displays.