Sheikh Salman had previously backed opposition to Infantino's failed plan to sell off the commercial rights to FIFA tournaments, including the World Cup, to private investors.
He had joined with the presidents of UEFA and CONCACAF to pen an open letter calling the FIFA Forward Enterprise plan formulated by Infantino a "fundamental breach of trust".
Infantino apologised at this month's FIFA Council and told attendees to submit any questions they had about his governance in writing so he could answer them at the next meeting.
In Sheikh Salman's opening remarks at the AFC's extraordinary congress in Tokyo, the Bahraini said the region supported Infantino.
"I think that we reaffirm our full commitment, of course, to supporting you and your leadership as you seek a new mandate as a FIFA president," he said in comments directed at the Swiss-Italian, who was present at the meeting.
"I think you've visited a lot of countries in Asia. I've spoken to a lot of members within this continent.
"I know your feeling. And I think your commitment is clear as well. Your support to Gianni is very clear."
Infantino is up for reelection in March as he seeks a fourth term until 2031.