Anthony Mifsud is being appointed Ombudsman, relinquishing his post as Auditor-General.
The appointment was announced by the prime minister, who said it had been agreed with the leader of the opposition.
Dr Muscat said Charles Deguara is being appointed Auditor-General.
The Accountant-General, Noel Camilleri, becomes the new Deputy Auditor-General.
Former Chief Justice Joseph Said Pullicino this morning gave a press conference to mark the end of his term as Ombudsman (see separate story).
Mr Mifsud had a busy time as Auditor-General, investigating, among other issues, oil procurement by Enemalta, the contract awarded to Henley and partners and the recent Gaffarena scandal.
The offices of the Ombudsman and the Auditor-General fall under the Office of the Speaker and the holders of the two offices are appointed in agreement between the government and the opposition.