The project was conceived back in the late 1990s by the then Dimmu Borgir keyboard player Kimberly Goss and In Flames guitarist Jesper Strömblad, who discussed the idea of a female fronted metal band during a joint world-tour. They were unable to take it any further until Kimberly left Borgir and moved to Sweden, where the first incarnation of Sinergy was born, with Arch Enemy bassist Sharlee D'Angelo, drummer Ronny Milianowicz, and Children Of Bodom guitarist Alexi "Wildchild" Laiho now on board. Under this line-up, the band released their debut album Beware The Heavens in 1999.
Although the band was starting to show promise, it was still considered a side-project of sorts, and with the majority of the members already part of more established groups, time management became a serious issue. Later that year, Kimberly had moved to Finland and Sinergy looked to be over, but she and Alexi wanted to continue the project, and thus they assembled a new, all-Finnish line-up. With Children Of Bodom guitarist Roope Ukk Latvala, drummer Tommi Lillman, and future Nightwish bassist & vocalist Marco Hietala filling in the remaining positions, the band forged ahead and released 2 albums under the line-up: To Hell And Back in 2000, and Suicide By My Side in 2002.
Various changes in the bassist and drummer departments followed Suicide By My Side's release. The band had later announced they were working on an album entitled "Sins Of The Past", but its release has been continously delayed and, for the time being, Sinergy looks to have stalled.