Before joining Kiss, St. John was a well known and respected teacher and guitarist for the Southern California cover band Front Page. After leaving Kiss, he formed a band called White Tiger, featuring David Donato (lead vocals), Michael Norton (Mark St-John's brother) (bass/backing vocals), and Brian James Fox (drums). Demos that the band had recorded with producer Andy Johns and guitarist Neil Citron, prior to Mark joining, apparently led to Donato's equally short tenure with another legendary band, Black Sabbath.
St. John was only with Kiss a short time, but he was featured on the album Animalize, the second album of the "unmasked" period. This turned out to be one of Kiss's most successful studio albums, aside from those made by the original lineup. St. John's only video appearance with Kiss is in the video for the hit single "Heaven's on Fire".
During the sessions for the album, which was recorded in mid-1984, St. John clashed with the other members of the band. He also developed arthritis (Reiter's Syndrome), which caused his hands and arms to swell. He was all but unable to perform live as a member of Kiss, and only played two full shows and one partial show during the Animalize tour, with Bruce Kulick playing the rest. Mark St. John was officially replaced by Bruce Kulick on December 8, 1984.
He is also the only Kiss member not to appear in on any album front cover, since the Animalize cover only features a tapestry of animal prints. However, he is posing with the rest of the band on the albums backside.
In January 1985 St. John teamed up with vocalist David Donato and drummer Barry Brandt of Angel to work on developing some demo ideas. By March he was playing live again, appearing at an all-star jam session at the FM Station Club. The lineup included Rudy Sarzo and Tommy Aldridge (Kiss Revolution, April/May 1985). Mark also performed at a sold-out audience at a benefit jazz concert for Greenpeace. Some of the legendary jazz musicians playing alongside Mark included the Steve Hooks Band, Stu Nevitt (Shadowfax), Slyde Hyde (Tom Scott/Supertramp), Al Aarons (Count Basie), plus other special all-star guests". (Kiss Force)
Mark and David soon formed White Tiger, becoming the first ex-Kiss guitarist to release an album (1986, predating both Ace Frehley and Vinnie Vincent's efforts). They had written most of the material for the album by mid-1985 and set out to complete a lineup with which to record. The band also included Mark's younger brother, Michael, on bass, but was completed with the addition of Brian James Fox on drums. While the independent release did well on that level selling some 50,000 copies, and the band gigged around California, Mark St John and his band White Tiger joined up with Garry Lane owner of Logic Productions who promoted many top bands in LA. Mark St. John and Garry Lane became good friends meeting for a second time at Trojan Studios in Garden Grove, California. That is where Mark and Garry came up with the idea to play the legendary club known as THE HOT SPOT located in Huntington Beach, California owned by Gennie Gromet who was the ex-wife of Dick Dale from the band Dick Dale and the Dale Tones. The band didn't manage to break and split while working on demos for a second album in 1988. St. John teamed up with Jeff Scott Soto in 1988 to make a demo. Mark also did some session work performing lead guitar on "Livin' for My Lord" on Ken Tamplin's 1990 album, Axe to Grind. Ken is an inspirational Christian rocker more famed for his involvement in the band Shout. Tamplin has also co-written material with Gene Simmons of Kiss. Mark also worked with former Knight Rider star David Hasselhoff, even appearing in his video, "Is Everyone Happy".
St. John made a demo in 1990 with fellow former Kiss member Peter Criss. This band, known as the Keep, became what was essentially White Tiger, with Peter Criss replacing Brian Fox on drums, and David Donato using the alias Michael McDonald. This lineup performed live just once, on May 2, 1990 at a drum clinic at the Guitar Center music store in Lawndale, California.
When the band started shopping their demo (credited as Peter Criss) around the response was universally negative. One cassette demo to circulate simply featured "Love for Sale", "Long Time", and "All Night Long", though they had also covered Lee Michaels' 1971 hit "Do You Know What I Mean", and had other original material such as "Between the Lines". By early 1991, the difficulty shopping the demo, and Mark's need to get on with making a living, led to friction between Peter and him, and he left the band (which eventually became Criss).
He was in a short lived band with Phil Naro called the Mark St. John Project that released a limited edition EP in 1999, and he also made an appearance on a KISS expo in New Jersey. He later released an all instrumental CD in 2003 called Magic Bullet Theory.
In later years, St. John did not make many public appearances. However, he was rumored to have returned to his pre-Kiss gig as a guitar instructor in the Southern California area.
St. John died on the morning of April 5, 2007, of a cerebral hemorrhage, making him the second ex-Kiss band member to die. The other member was Eric Carr, who died of heart cancer in 1991 (although Eric was a current member of Kiss at the time of his passing). Mark is survived by his siblings Michael and Kathleen as well as his parents Les and Terry Norton who reside in Orange County, California.