One Nation Underground is the third album by Ill Niño and their final studio album released through Roadrunner. It debuted at No. 101 on the Billboard Top 200 with first week sales of nearly 11,000.[4] Its sales of approximately 210,000 are well down on the near Gold selling Confession. The album features several elements and influences of metalcore, groove metal and even tribal music. This is the band's last album with guitarist Jardel Paisante.
When the band announced the track list for this album, there was a cover of the Peter Gabriel song "Red Rain" on the album, as track 13. It was cut from the official release, though it was later released on The Undercover Sessions. The instrumental song "Barely Breathing" was added to the official release instead.