US President Donald Trump awarded the US Legion of Merit, Degree Chief Commander, to Kuwaiti Emir Sheikh Sabah Al Ahmad Al Sabah, the White House said in a statement on Friday.
The White House said that it was the first time the honour has been given out since 1991.
The 91-year-old emir arrived in the United States in July to complete medical treatment, the Kuwaiti state news agency said at the time, adding that he was in stable condition after having undergone successful surgery in July.
The emir's eldest son, Sheikh Nasser Sabah Al Ahmad Al Jaber Al Sabah, accepted the award on behalf of his father at a private ceremony with Mr Trump on Friday.
The White House praised the emir as an "unwavering friend and partner to the United States" who gave "indispensable support to the United States throughout Operation Iraqi Freedom, Operation Enduring Freedom, and the Defeat ISIS campaign."
Operation Iraqi Freedom refers to the 2003 US invasion of Iraq to oust former Iraqi dictator Saddam Hussein; Operation Enduring Freedom to the 2001 US-led military operation that drove the Taliban from power in Afghanistan; and the Defeat ISIS campaign to the coalition effort to end the militant group's control of territory in Syria and Iraq.
The White House described the award given to the Kuwaiti emir on Friday as a rare, prestigious decoration that can only be bestowed by the president, typically to foreign heads of state or government.
On Monday, Kuwait's prime minister told the Kuwaiti cabinet of the improvement of the emir's health.
In July, Kuwait's cabinet tweeted that the emir arrived at Rochester airport in the United States, without specifying which US city of that name. The main campus of the Mayo Clinic, among the top US medical centres, is in Rochester, Minnesota.