The leader released a statement congratulating Iraqis "in the wake of heroes taking control of Qaim and liberating it in record time."
The news of Qaim's liberation comes the same day that the Syrian military reportedly took back control of Deir Ezzor
, the terror group's last-held city in that country.
Brig. Gen. Yahya Rasoul, a spokesman for Joint Operations Command, confirmed to CNN that Qaim had been "fully liberated."
Qaim is located in the western part of Anbar province, along the Iraq-Syria border, where ISIS holds the last of its territory -- the remnants of its so-called caliphate.
Iraqi forces had surrounded the last of the ISIS fighters in nearby towns Rawa and Romana, as well as surrounding areas north of the Euphrates River on Qaim's outskirts, Rasoul said.
The US-led coalition congratulated the Iraqi government and the Iraqi Security Forces (ISF) in a statement.
"Iraqi Security Forces have fought hard to reach this point, and their battle-proven troops captured ISIS's last Iraqi stronghold swiftly and thoroughly," said Maj. Gen. Robert P. White with Operation Inherent Resolve.
"The threat remains, and there is still hard work to do, but we will continue to stand side-by-side with the Iraqi Government and the ISF to ensure the enduring defeat of ISIS," White said.
Deir Ezzor was also fully liberated on Friday, according to Syrian state media outlet SANA.
"The Syrian Arab Army restored security and stability to the entire city of Deir Ezzor after eliminating Daesh's last stronghold in it," the state media said, using the Arabic name for ISIS.
Gaining control of Deir Ezzor
was a significant victory for the Syrian government, and followed ISIS' ousting from Raqqa, the de facto capital of the caliphate.
The ISIS losses in Deir Ezzor and Qaim further condensed and compressed ISIS territory, squeezing the caliphate into a smaller and narrower area.