CA announced on Monday Oliver would take over as high performance chief of the men's and women's national teams, with Ginn to oversee state and talent pathway programmes.
The polarising Howard was sacked in November in the wake of a scathing governance review of CA following the ball-tampering scandal in South Africa.
CA announced in March that Howard's role would be split in two.
Oliver was appointed high performance manager at Western Australia state in 2012.
Ginn, a member of Australia's iconic "Oarsome Foursome" which won gold at the 1996 Atlanta Games, was appointed high performance boss of Cricket Tasmania two years ago.
The pair begin their new roles on July 29, two days before Australia play Joe Root's England in the first test of the Ashes.
Belinda Clark, who has been serving as interim team performance boss since Howard's departure last year, would resume her role as executive general manager of community cricket at the conclusion of the ongoing World Cup, CA said.
(Reporting by Ian Ransom; Editing by Peter Rutherford)
