During 1995, Kiske participated as a guest on Gamma Ray’s (Kai Hansen’s band, formed after his departure from Helloween in late 1988) Land of the Free album, singing lead vocals on the song “Time To Break Free” and additional vocals on the title track.
In 2000, Kiske was asked to participate on the Avantasia project The Metal Opera in the role of Lugaid Vandroiy, which he agreed to do, but only under the nickname of Ernie. The nickname was printed on the back of the first CD, but not on the second, where he was featured under his real name. Michael said in interviews that, at that time, he did not want people to link him to heavy metal anymore. He had a main role in the concept of the Metal Opera albums and sang on a total of 7 songs.
During 2002, Kiske sang the song “Key to the Universe”, which was featured on Timo Tolkki’s (guitarist of the band Stratovarius) solo album Hymn to Life. In the same year, Michael also sang the duet “Heroes” (together with Jorn Lande), featured on Masterplan’s self titled debut album.
In 2003, Sascha Paeth (Heaven’s Gate) asked Michael to work on the Metal Opera: AINA. Michael sings in the role of narrator on 4 songs: “Silver Maiden” & “Serendipity” by himself and a bit in “Revelations” and “Restoration”. Most of the tracks are symphonic like the songs from the second Kiske solo album “Shadowfights” & “Easy”. They could be included in a “Walt Disney” Soundtrack.
In 2004, Michael sang the duet “The Encounter”, together with the female vocalist of the band Thalion on their debut album Another Sun.
During 2005, Michael was a guest on the heavy metal album Execution by the band Tribuzy, singing on the duet “Absolution”. Following this participation Kiske sang another duet, entitled “Judas At The Opera”, together with Tobias Sammet (vocalist of the band Edguy and founder of the Avantasia project) on Edguy’s Superheroes EP.
In 2007, Michael sang on the song “Breathe in Water”, together with the female vocalist of the band Indigo Dying on their self titled debut album. During the same year, he recorded guest vocals for two Avantasia tracks; “Promised Land”, which appeared on the Lost in Space Part II EP and “Lost In Space [Extended Version]”, which appeared on the Lost in Space Part I & II compilation album.
During 2008, Kiske took part on the Avantasia album The Scarecrow, singing lead on the track “Shelter from the Rain” and backing on the title track and on “What Kind Of Love”. In 2008 there was another collaboration with Timo Tolkki for his new band Revolution Renaissance, in which Michael Kiske sang 5 songs. Later there was another EP released, which included some acoustic remixes of the songs with Michael Kiske.
In 2009, Michael was a guest on Trick or Treat’s album Tin Soldiers, singing all vocals for the song “Hello Moon” and additional lead vocals on the duet “Tears against Your Smile”.
In 2010, he did another cooperation with Kai Hansen and Gamma Ray with guest vocals for the chorus of the song “All You Need To Know”, featured on Gamma Ray’s To The Metal album.
In 2012, Michael sang the song “The Ethereal Dream (Reprise)”, featured on the album 34613 by the project Tomorrow’s Outlook.
In 2013 there was a collaboration for Timo Tolkki’s Avalon in which Michael sings on the song ‘The Land of New Hope’. Another collaboration in this year was for the Itallian band Infinita Symphonia, where he sings the song ‘Fly’ on the album ‘Infinita Symphonia’.