Mount Edgar Thomson is set in the Ben Ohau Range of the Southern Alps and is situated in the Canterbury Region of South Island.

[5] Topographic relief is significant as the summit rises 1,380 metres (4,528 feet) above Hoophorn Stream in 1.5 kilometres.

[3] The mountain's toponym was applied by Jane Thomson to honour her only child, Edgar (1881–1904), who had died in 1904 at age 23 from a football injury.

[3][6] Edgar Thomson died at the Wellington Hospital after sustaining a head injury while playing a rugby match.

The months of December through February offer the most favourable weather for viewing or climbing this peak.