“The Joint Operations Command announces the complete liberation of the Rutba district,” it said in a statement.
Special forces, soldiers and police took part in the operation, the statement said.
Iraqi forces launched the drive to retake Rutba, located in western Anbar province along the main road to Jordan, three days earlier.
IS overran large areas in north and west of Baghdad in June 2014, and later made further advances in Anbar, seizing its capital Ramadi in 2015.
Iraqi forces have since regained significant ground from the jihadists, securing the Ramadi area earlier this year and retaking the town of Heet last month.
But parts of Anbar — including its second city Fallujah — are still under IS control, as is most of Nineveh province, to its north.