[5] It was discovered in 1950 by Robert George Harrington and Albert George Wilson, from the Mount Wilson and Palomar Observatories in California.

In 2007 a team of 15 scientists observed Leo II through the 8.2 meter Subaru optical-infrared telescope in Mauna Kea, Hawaii.

Over 2 nights, 90 minutes of exposures were taken and 82,252 stars were detected down to a visible magnitude of 26.

They found that Leo II consists largely of metal-poor older stars, a sign that it has survived the galactic cannibalism under which massive galaxies (e.g., the Milky Way) consume smaller galaxies to attain their extensive size.

[6] Observation at ESO estimates Leo II's mass to be (2.7 ± 0.5)×107 M⊙.