Magnus was born in Gothenburg, Sweden on June 10th. At the young age of 10; he started to play the flute. By the age of 15, the bass became his first love. He found himself mesmerized by the magic of Kiss’s music and Gene Simmon’s playing, which became his main inspiration for wanting to pursue a career in music. He started his first band called, "Lazy Babes" with some friends and got to play at his school.
In 1980 Magnus recorded his first album with the band, "Shame". They released one single. At the age of 18 he joined his first serious band. A 50’s rock band called Kung Sune. Their first single; "Sunes bar och grill" was released in 1982.
In 1983 Magnus played with the "Chris Mentzer" group; Later changing their name to Northern Light. Between 1985 and 1988 Magnus played with a pop rock band called Von Rosen. In 1987 they released their first single "Like a Dream" , followed by "Someone Like You" in 1988 . In 1990 Magnus did his first US tour as the bassist of a hard rock group called "The Stuart Smith’s Midnight.
In 1993 he played with the Swedish guitar legend Bo Winberg and the Spotnics on tour until June. In the same year he joined the Billionaires Boys Club with Marc Boals, Anders Johansson and the former Accept guitar player Jörg Fischer. They released an album called "Something Wicked Comes" The album was followed by a tour.
In 1995 he recorded with Keegan the "Mind No Mind" album. Magnus also did a tour in France. Included were television performances with Ten Times Worse (Greg Hanssen). In 1997 he joined HammerFall 3 months before the release of their debut album "Glory to the Brave". Legacy of Kings, the second album of HammerFall was released in 1998. Two more singles: "Heeding the Call"(98’) and " I Want Out"(99’). The Templars World Crusade in 1998-1999 was the first world tour of HammerFall.
After the HammerFall tour, Magnus went to Brazil to perform his first solo tour playing jazz and fusion flavored solo bass. This tour won over not only HammFall fans, but critics also. Beside the solo tour, HammerFall release his first video called "The First Crusade".
In May of 2000 the band went to Nashville, Tennessee/USA to record their third album at Michael Wagener Studios. After some months "Renegade" was released which fueled their second world tour ‘till August 2001. The last show was in Wacken Open Air, the biggest metal festival in Germany.
"Imagine a Place", the first solo album of Magnus Rosén (featuring Biggi Vinkeloe) was released in February 2001. This critically acclaimed album housed almost 71 minutes of eclectic instrumental pieces varying from blues, Jazz and Fusion. The album received such high appraise from the press in Europe, Canada and Brazil. Magnus and Biggi traveled to San Francisco (USA) at two occasions for concerts.
The second solo album of Magnus is "Reminiscence". Once again with his partner Biggi Vinkeloe on the sax and flute and the drummer Don Robinson. Reminiscence was released in Europe and South America.
After a successful Japanese solo tour in July 02' Magnus hit the studios to record "CrimsonThunder", the 4th studio album with the band HammerFall. "Hearts on Fire" is the first single off the album.