After graduation, he spent the next five years in Mexico performing geological and botanical research.
Here he collected numerous new species of plants, particularly cacti.
In 1840 Galeotti was offered a position teaching botany at the University of Brussels, but turned down the offer, preferring to work at his nursery outside of Brussels, from where he imported Mexican flora for sell in Europe.
During this time period, he collaborated with botanist Martin Martens (1797-1863) on scientific study of species native to Mexico.
After Galeotti's death in 1858, his personal Mexican herbarium was purchased from his widow by the Jardin botanique de Bruxelles.
In August 1838, while in Mexico, he and a group of other botanists explored the slopes of Pico de Orizaba, the tallest mountain in Mexico.
The genus Galeottia of the family Orchidaceae is named in his honor.