Seeliger was elected an Associate of the Royal Astronomical Society in 1892, and President of the Astronomische Gesellschaft from 1897 to 1921.

His contributions to astronomy include an explanation of the anomalous motion of the perihelion of Mercury (later one of the main tests of general relativity), a theory of nova coming from the collision of a star with a cloud of gas, and his confirmation of James Clerk Maxwell's theories of the composition of the rings of Saturn by studying variations in their albedo.

Seeliger's views on the dimensions of our galaxy were consistent with Jacobus Kapteyn's later studies.

The brightening of Saturn's rings at opposition is known as the Seeliger Effect, to acknowledge his pioneering research in this field.

His PhD students were (after Mathematics Genealogy Project, Hugo Hans von Seeliger) :