Kilkenny 0-08 London 4-13
London had a comfortable win at Freshford as they set up a Tommy Murphy Cup quarter-final against Sligo next Saturday.
The Exiles grabbed goals through Alan Raftery, Marty Hughes and Owen Henry to lead by 3-07 to 0-00 after 29 minutes.
Kilkenny responded with points from Eddie Brennan and David Herity (0-02) before the interval.
But despite Donal Conlon's 53rd-minute red card and a second yellow for Eamon O Cuiv, London failed to let up and rubberstamped the victory with an Andy Hayes goal.
Scorers - Kilkenny: E Brennan 0-05 (0-02f), D Herity 0-3 (0-03f)
London: A Hayes 1-07 (0-02f), A Rafterty, O Henry 1-01 each, M Hughes 1-00, H Murphy 0-02, B Comer, R Dempsey 0-01 each
KILKENNY: JJ O'Sullivan; A Mackey, P Donovan, M Dowling; M Morrissey, A Murphy, L Brennan; M Mahony, J Maher; A McGovern, D Herity, S Mahony; M Saunders, E Brennan, M Grace.
Subs used: JJ Brennan for Saunders (52 mins), K Slattery for Grace (55), P Donnelly for J Maher, M Lyons for McGovern (both 60).
LONDON: E Byrne; R Morgan, D Conlon, G O'Hare; P McDermott, E O Cuiv, B Comer; P Geraghty, D Gallagher; H Murphy, A Raftery, O Henry; S Maguire, M Hughes, A Hayes.
Subs used: O Coffey for Henry (half-time), R Dempsey for M Hughes (50 mins).
Referee: Eddie Craul (Wicklow)