"I think that renumeration is too high," he later told reporters in Canberra.
Mr Turnbull acknowledged it was Australia Post board's prerogative to set salaries and that Mr Fahour had a big job overseeing a large government-owned entity which had improved its operating business.
"In my view, I say this as someone who spent most of his life in the business world before I came into politics, I think it is a very big salary for that job."
Deputy Prime Minister Barnaby Joyce said the figure was untenable and the government was "hot to trot" to try and turn it around.
"That's out of the ballpark," he told 2GB radio.
Australia Post had argued revealing the salaries could expose its executives to unwarranted media attention and cause brand damage.
It preferred to release the information on a confidential basis.
But committee chairman James Paterson wrote to the company on Tuesday informing it the documents would be publicly released.
"Any potential issues of personal safety and security do not appear to be compelling reasons to withhold publication," he said.
Crossbench senator Nick Xenophon noted Mr Fahour's remuneration was more than 10 times that paid to the prime minister.
"I think a lot of people will scratch their heads," he said.
Labor senator Doug Cameron questioned whether the executive payouts were value for money, adding Australian bosses were generally overpaid.
"They try and push Bangladesh wage rates and conditions for their workers but Wall Street pay and conditions for the executives," he said.
Australia Post insists its executive team's remuneration is set by the board and not management.
"Mr Fahour's total remuneration package takes into account the size and complexity of the organisation, which has an annual turnover of more than $6 billion," it said in a statement.
His remuneration in the previous financial year included a performance-based bonus in line with the company returning to profit and he did not receive a bonus in the year before that, it said.
"Since 2007 Australia Post has paid more than A$6.3 billion in dividends and taxes to the federal government," Australia Post said.
It noted the company did not receive taxpayer funding.
