Dignam was born in the Holles Street Hospital in Dublin in May of 1960, and grew up in the north Dublin suburb of Finglas.

Dignam studied the classical art of Bel Canto singing with teacher Frank Merriman at the Bel Canto House School of Singing in Dublin, Ireland.

Dignam turned to heroin in the 1980s, and his involvement with the drug caused the conflicts which led to his eventual separation with the band Aslan.

On Wednesday September 7, 1988, The Star newspaper headlined "ASLAN: IT'S THE END" informing the public about Dignam's separation from Aslan. The remaining members of the band continued Aslan for some time with a new lead singer, Eamon Doyle, before the band eventually split. Dignam went solo with guitarist Conor Goff, forming Dignam & Goff.

However, on Jully 11, 1993 Aslan reformed, for what was supposed to be a 'once off gig' in Finglas.  With the spark reignited and with new material, Aslan continued and became one of Ireland's most successful and hard-working bands.

Dignam related his story of drug addction in an autobiography entitled This is Christy Dignam written with journalist Neil Fetherstonhaugh and published by Merlin Publishing. Dignam's book is so candid and honest about the pain and suffering of drug addiction that it has led one reviewer to say it “should be required reading for anyone hovering on the edges of the drug culture.”