The six were expected to plead guilty and cooperate in the government's case, the New Orleans (La.) Times-Picayune reported Wednesday.
The investigation focuses on an $81 million contract between New Orleans and Milwaukee-based Johnson Controls Inc. that was intended to reduce city energy bills.
The six charged Tuesday include Stan "Pampy" Barre, a restaurateur and Morial confidant, who reportedly received $800,000 for little or no work.
Also charged were ex-city Property Management Director Kerry DeCay and former Johnson Controls Project Manager Terry Songy, who reportedly each received at least $100,000 in cash and gifts.
The charges add to June indictments against a former city official and three businessmen.
Morial, now president of the National Urban League in New York, has not been implicated in the scheme and repeatedly declined comment.