Galway tore into the Cats from the first whistle and Joe Canning's goal after three minutes underlined their intent. The Portumna ace was superb once more as he would finish the day with 1-10 to his name.
Galway had 1-6 on the board to no reply after 17 minutes and things got even better for the Connacht side as they opened up a 2-12 to 0-4 lead at the break thanks to another excellent goal from David Burke.
Kilkenny looked shell shocked and, amazingly, managed just one point from play in the opening 35 minutes.
They improved vastly on the restart and goals from Richie Hogan and Henry Shefflin gave them hope but with Galway in determined mood, Kilkenny didn't look like they could reel in Anthony Cunningham's men.
To their credit they kept trying and continued to probe a Galway defence that had conceded 7-27 against Offaly and Westmeath in their previous two championship outings.
However, they proved resolute on this occasion with Johnny Coen in outstanding form and when Matthew Ruth drove a late goal chance wide, Kilkenny's already fading hopes evaporated completely.
It was fitting that two of Galway's outstanding performers - Cyril Donnellan and Canning - landed the last scores as Kilkenny's seven year vice like grip on the Leinster title was ended.
Galway: J Canning 1-10 (0-7 frees), D Burke 1-2, C Donnellan 0-5, N Burke 0-2, D Hayes, D Collins 0-1 each.
Kilkenny: H Shefflin 1-8 (0-7 frees), R Hogan 1-0, R Power 0-2, M Rice 0-1.
Galway: J Skehill 7; F Moore 8, K Hynes 7, J Coen 8; D Collins 8, T Og Regan 8, N Donoghue 8; I Tannian 7, A Smith 8; N Burke 8, D Burke 8, D Hayes 8; J Canning 9, C Cooney 7, C Donnellan 9.
Subs: J Glynn 7 for C Cooney (53), J Regan 7 for Tannian (57), T Haran 6 for N Burke (61), J Cooney for Donnellan (71)
Kilkenny: D Herity 6; P Murphy 6, N Hickey 6, J Tyrrell 5; T Walsh 5, B Hogan 5, R Doyle 6; C Buckley 6, P Hogan 5; H Shefflin 7, TJ Reid 5, E Larkin 5, R Power 6, R Hogan 6.
Subs: A Fogarty 6 for Fennelly (22), M Rice 7 for P Hogan (26), M Ruth for Reid (57).
Referee: J McGrath (Westmeath)