His father, Gustav Robert Groß, was a railway industrialist, and a participant in the Frankfurt Parliament, as part of the 1848 revolutions across the German Confederation.
From 1911, Groß was chairman of the Deutscher Nationalverband, a broad coalition of German nationalist and liberal political parties that was formed to contest the 1911 election to the Imperial Council.
In his function as president of the House of Deputies, Gustav Groß delivered the "nine minute closing address" at the session on 12 November 1918, the day after the abdication of Emperor Charles I.
As proposed by Groß, a motion "to vote for no day for the next session" (keinen Tag für die nächste Sitzung zu bestimmen) was passed.
As chairman of the Greater German People's Party, Groß was a member of the Provisional National Assembly from 21 October 1918 to 16 February 1919.