The verdict against Said Bouteflika -- already serving time in a different case -- is the latest in a string of investigations into corruption during his brother's two decades in power, launched by the judiciary since mass protests in 2019 forced the former president to resign.
Algerian news website Interlignes said the Sidi M'hamed court in Algiers has also given a 12-year sentence to two other defendants - businessman Ahmed Mazouz and construction tycoon Ali Haddad, who is also already in prison on other charges.
Mahieddine Tahkout, a former car industry boss and one of the most influential business figures of the Bouteflika era, has been sentenced to 15 years, the report said.
Three other ex-tycoons, brothers Reda, Noah-Tarek and Abdelkader-Karim Kouninef, have been sentenced to 10 years each, it added.
The Kouninef brothers, who were close to the ousted president, had already been sentenced to 12-16 years in another corruption case.
In June, Said Bouteflika was given an eight-year sentence for corruption.
Sentences issued by Algerian courts are not added up, with only the longest sentence actually served.