The band was formed in 1999 in Pori, Finland by singer/lead guitarist Jori Haukio, guitarist Jarkko Kokko and keyboardist Toni Nummelin. Drummer Mikko Sipola joined in late 1999, soon followed by the arrival of new vocalist Ville Viljanen in early 2000 when Haukio decided to focus on his guitar work. Bassist Teemu Heinola was not appointed until after the band's first demo, Before Birth, which attracted attention from French record label Listenable Records in 2001.

One year and two demos later, Mors Principium Est signed a three-album contract with Listenable Records completed by the album Liberation = Termination released in March 2007.

The band announced on April 25, 2007 the new lineup of the band. Karri Kuisma joined the band as the rhythm guitarist in 2006 and Lead guitarist Tomy Laisto joined the band in 2007. Jarkko Kokko will still be a member of M.P.E. but he will not play any live shows.

On March 2011 the band stated that members Tomy Laisto and Kalle Aaltonen had parted ways to pursue other ventures. The band stated "If we still want to continue with Mors Principium Est, we need new guitar players" and proceeded to ask for anyone who could try out around the world to do so.

On April 30, 2011 the band announced on their website that Andy Gillion had been recruited as the first replacement guitarist. On September 29, 2011 the band announced on their website that Andhe Chandler had been recruited as the second replacement guitarist.