He contributed theatre reviews to the Courrier de Lyon and wrote for the Journal du Rhône, directed by his father.
In 1867 he was appointed Attorney General at Paris in place of Louis François Chabanacy de Marnas(fr).
[2] In the trial of Prince Pierre Napoléon Bonaparte for homicide on 21 May 1871 Grandperret served as Attorney General at the High Court convened in Tours.
Grandperret was the author of a report sent to the Keeper of the Seals on 5 May 1870 on a "conspiracy" against the life of the emperor discovered shortly before the plebiscite.
He was reappointed Attorney General at the high court in Blois convened in July 1870 to investigate the conspiracy.
[2] For a period Louis Le Provost de Launay (1850–1912), future deputy and senator, was Grandperret's secretary.
[3] On 15 November 1877 Grandperret was elected by the coalition of the right as Life Senator in place of Alphonse Lepetit(fr), who had died.