C.J. Snare -- better known as the lead singer of hard rock band FireHouse -- has died ... TMZ has confirmed.

Snare's daughter, Heather, tells us ... her father passed away Friday afternoon after a lengthy cancer battle. She says his official cause of death is cardiac arrest.

Snare helped form FireHouse in 1987 after his former group -- Maxx Warrior -- broke up. He stayed with the band for nearly 40 years until his death.

C.J. played keyboards and sang on all seven albums the group has released ... including their self-titled debut album which went double platinum in the United States.

Among the group's hits ... "I Live My Life For You," "Here For You," "When I Look Into Your Eyes," "Don't Treat Me Bad," "Reach for the Sky" and many more.

Perry Richardson -- another co-founder and the former bassist for the group -- tells TMZ ... Snare was one of the great voices in rock history, and he will be greatly missed.

C.J. is survived by three children. He was 64.

RIP