Iraqi forces and the armed volunteers entered the city on Sunday, where at leat 12,000 people have been trapped for over two months with dwindling food and water.
"Our forces entered Amerli and broke the siege," security spokesman Lieutenant General Qassem Atta told the AFP news agency.
Adel al-Bayati, mayor of Amerli, also confirmed the report to Reuters news agency saying that government forces are now "inside" the town, adding that it "will definitely relieve the suffering of residents."
Armed residents had managed to fend off attacks by the ISIL, who encircled the town and regarded its majority population as apostates.
US jets and drones have also attacked the ISIL group's positions near Iraq's Mosul Dam.