The band originally also included guitarist Neal Schon of Journey and Bad English, bassist Todd Jensen (ex-Sequel), and drummer Deen Castronovo.

[citation needed] Their debut album Double Eclipse was released on April 28, 1992, and was well received by audiences and had extensive radio airplay at the time.

On November 2, 1992, the Hardline song "In the Hands of Time" was played in its entirety during a montage on the "Princess of Tides" episode of the TV serial, Baywatch.

[citation needed] After Hardline lost its record deal, Neal Schon departed to begin several projects before finally rejoining Journey.

Former Jag Panzer and Shrapnel Records legend Joey Tafolla was approached to join but was unable to participate at the time due to his work schedule, consisting primarily of building his southern California merchandising company.

Rock suggested his friend, LA session bassist Christopher Maloney, who had previously worked with Dweezil Zappa, to handle the bass duties on II.

Due to Maloney's focus on promoting his solo album Control as well as working with other artists, he was unable to join the band for "The Gods Festival" in Bradford, England in June 2002.

They initially asked ex Ozzy Osbourne and Quiet Riot bassist Rudy Sarzo to join the band, but he was busy with other projects at the time.

Instead, White Fang bassist Jamie Brown took his place, with Atma Anur on drums and returning member Michael T Ross on keyboards.

On December 22, 2011, Johnny Gioeli confirmed, via the Frontiers Records official site, that it had been announced that he and Italian keyboard player and producer Alessandro Del Vecchio of Edge of Forever and Eden's Curse would release Hardline's fourth studio album in mid-2012.

Via Frontiers Records's official electronic press kit for Danger Zone, Johnny Gioeli and Alessandro Del Vecchio announced that "by the time you watch this, we will already be working on the next [album]."

It also contains a cover of the Queen song "Who Wants To Live Forever" as Gioeli often exclaims that Freddie Mercury is a huge influence on his voice, and many Hardline fans often compare the two singers that sound alike.

An extensive tour of the Life album followed, which began in 2019 majorly across Europe and Germany, and still continues in 2020, but was halted in the middle of the year due to the COVID-19 pandemic.

On April 29, 2021, with the first single, "Fuel to the Fire", the band had announced the new studio album, Heart, Mind and Soul, that was released on July 9, 2021, via Frontiers Music SRL.