He is known for his progressive rock-influenced songwriting style and his frequent use of both clean baritone and growled vocals. On stage, he is notably interactive with audiences, frequently making the audiences laugh with his dry humour, and giving humorous anecdotes between songs.
A native of Stockholm, Mikael Åkerfeldt was the vocalist for Eruption, a death metal band which he formed in 1988 at 14 years old. After Eruption came to an end in 1990, he joined Opeth, ostensibly as a bassist. When vocalist David Isberg insisted Åkerfeldt join the band, all other members left. Isberg assumed guitar duties, and when he left Opeth two years later, Åkerfeldt replaced him as the vocalist. Åkerfeldt performed the death vocals on Katatonia's album Brave Murder Day and Sounds of Decay EP.
Åkerfeldt is a collector of obscure 1970s rock and heavy metal albums. He also tends to show his influence from these obscure bands, making reference to them in Opeth album titles such as Blackwater Park, Still Life and My Arms, Your Hearse, as well as songs such as "Master's Apprentices." He is also influenced extensively by jazz, as well as the musician Ritchie Blackmore.
On 15 August 2003, Mikael Åkerfeldt married his longtime girlfriend, Anna Sandberg. On 13 September 2004, Anna gave birth to a daughter whom they named Melinda. The couple had their second daughter, Mirjam Ebba Maria Åkerfeldt, on 28 October 2007.
Mikael Åkerfeldt revealed in September 2009 that he is contemplating recording a singer-songwriter acoustic solo album.
"I've always been wanting to do a thing like that. I've got a bunch of lovely acoustic guitars back I wanna use more. Even though Opeth could probably do an album like that, I wanna do it on my own, and in that sense, I want to record it on my own — in my house, basically. I think I can do it well. I think I can do a good album like that."
"I'd like to maybe simplify it even more [than the Opeth acoustic stuff], and have it just chords playing, and maybe some finger-picking stuff, so I could be able to perform it if I would wanna do that. So I don't want it to be lots of tracks, like overdubbing guitars with lots of melodies; I want it to be fairly simplistic so if I wanted to, I could play it live on my own... on a stool. [laughs]"
Mikael Åkerfeldt with Opeth at Ruisrock 2008 in Turku, Finland.
Åkerfeldt uses 3 different tunings: E Standard, Drop D and Open D minor 9 (D-A-D-F-A-E). He has almost exclusively used PRS guitars since the Deliverance/Damnation era and has his own signature model.
Dream Theater: Åkerfeldt performs a spoken word part in "Repentance" on their 2007 album Systematic Chaos. He also sang the second verse of the same song on its first and to date only live performance, during the Progressive Nation 2008 tour. He also performed the growled verse of their song "A Nightmare to Remember" with the band live.
Ihsahn: Åkerfeldt performs on the song "Unhealer" from the 2008 album angL.
OSI: Åkerfeldt performs lead vocals on the track "Stockholm" for OSI's 2009 album, Blood.
Porcupine Tree: Åkerfeldt sings backing vocals on "Deadwing", "Lazarus", "Shesmovedon" and "Arriving Somewhere But Not Here" and plays a guitar solo on "Arriving Somewhere But Not Here" on the 2005 album Deadwing.