Iran's participation at this year's tournament in Canada, Mexico and the United States has been shrouded in uncertainty since the eruption of war in the Middle East in February following strikes by the United States and Israel.
Infantino, who has repeatedly stated that Iran will be at the World Cup, underscored that stance at the start of his address to delegates in Vancouver.
"Let me start by the outset, confirming straightaway that of course Iran will be participating at the FIFA World Cup 2026," Infantino said.
"And of course, Iran will play (in) the United States of America."
Iranian officials had floated the idea of shifting their group games from the United States to Mexico, but that proposal had already been nixed by Infantino.
In a further twist last week, Italy-born US special envoy Paolo Zampolli was reported to have floated the idea of Italy taking Iran's World Cup place.
The US government later distanced itself from that proposal, with US Secretary of State Marco Rubio saying Iran's footballers would be welcome.
But the tension surrounding Iran's World Cup participation rumbled into the build-up to Thursday's FIFA Congress.
Iran was the only absentee from the 211-member congress as Thursday's meeting got underway after a clash with Canadian border officials earlier this week.
Officials from the Iranian football federation (FFIRI) abruptly left Canada after landing in Toronto, abandoning their onward trip to Vancouver.
Iranian media said FFIRI president Mehdi Taj - a former member of Tehran's Islamic Revolutionary Guard Corps (IRGC) - and two colleagues flew home after being "insulted" by Canadian immigration officers.
Canada, which designated the IRGC a terrorist organisation in 2024, said Wednesday that individuals linked to the force were "inadmissible."
"While we cannot comment on individual cases due to privacy laws, the government has been clear and consistent: IRGC officials are inadmissible to Canada and have no place in our country," Canada's immigration agency said in a statement.
Iran, who are due to be based in Tucson, Arizona during the World Cup, face New Zealand, Belgium and Egypt in Group G.
The Iranians open their World Cup campaign against New Zealand in Los Angeles on June 15th.
