Poulsen grew up in Ringsted, Denmark which is about a 40 miles (63 kilometers) from Copenhagen in a working-class family. He has a twin sister and two older sisters, who are also twins. His parents were big fans of Elvis Presley, Jerry Lee Lewis, Johnny Cash, and Chuck Berry. As a teenager, he got in touch with metal music like Metallica, Iron Maiden, Whitesnake, Deep Purple, Iced Earth and Black Sabbath. At the age of 17, he moved to Copenhagen and formed his first band Dominus. Poulsen stated a major influence during this period was Chuck Schuldiner and his band Death.
Dominus released four records between 1994 and 2000. The band split-up a year later as Poulsen was fed up with death metal music and the death metal scene. He wrote new songs with a more rock'n'roll approach and established Volbeat. After releasing two demos, their debut album The Strength / The Sound / The Songs reached number 18 in the Danish charts and became the first album of a Danish metal band in 20 years to enter the top 20. On 22 April 2006, Poulsen performed with some of Elvis Presley's studio musicians in Copenhagen. Volbeat's sophomore record Rock the Rebel / Metal the Devil and their third effort Guitar Gangsters & Cadillac Blood went straight to number 1 in the Danish charts.
Poulsen later showed his affinity towards Social Distortion, and taking cues from a "new influence" created Volbeat's distinct sound.
Poulsen's father, who was a big fan of Volbeat, died on 27 June 2008, shortly before the release of Guitar Gangsters & Cadillac Blood. The song "Light a Way" from the same album was played at his funeral. A week after the death of his father got Poulsen tattooed his parents' names, Jørn and Deposits, on the fingers with a letter on each finger except the thumb. Later songs, like "Fallen" (Beyond Hell/Above Heaven) and "Our Loved Ones" (Outlaw Gentleman & Shady Ladies) have been influenced by Poulsen his father.
March 2010 Poulsen was married at Graceland, Memphis, to his wife Lina. But got divorced in 2015.
In 2012, Poulsen is doing a liner note for the Relapse Records reissue of Death's 1990 album Spiritual Healing, which he considers one of his favorite albums.
In 2014 Poulsen did a verse in Highwayman, a Jimmy Webb song covered by Iced Earth on the album Plagues of Babylon. Iced Earth's cover of Highwayman was done in the format of the same song covered by country Supergroup "The Highwaymen". Poulsen sings the same verse that Johnny Cash sings in the song.
Poulsen primarily plays Gibson SG guitars, first a Tony Iommi signature model but later a GT-model with Seymour Duncan pickups, through a Marshall JCM800 2210 model. He also sometimes plays an ESP Eclipse and a Gibson Les Paul Goldtop. The effects Poulsen uses are an Ibanez Tube Screamer, a noise suppressor, a vintage equalizer and a maximizer pedal.
In 2006, Poulsen was nominated in the categories Singer of the year and Composer of the year at the annual Steppeulven awards. Two years later, he was nominated in the category Best singer at the Danish Music Awards.