Sligo flew out of the traps in Ruislip to book a Connacht semi-final date with Galway or Mayo on 3 June.
The Yeats County suffered a shock defeat on their last visit to London in 2013 but there was never any danger of a repeat thanks to a ruthless first-half display.
Adrian Marren’s 24th-minute penalty put Sligo eight points in front and they didn’t look back, with Marren finishing with 1-06 and 11 different players getting on the scoresheet.
London lined up with seven English-born players in their starting line-up, along with Sligo native David Carrabine whose brother Sean came off the bench for the visitors.
But while there were flashes of quality from the hosts, their lack of end product meant the game was effectively over by the interval.
London failed to muster a single score from their first seven attempts on goal, while Sligo came away with five points from as many shots in the opening 10 minutes to take control.
The gap was widened further when Gerard O’Kelly-Lynch was taken out by Gavin McEvoy inside the area. The London goalkeeper was given a yellow card before Marren sent him the wrong way from the penalty spot.
Trailing by 10 points, London kept battling and they produced the move of the game to create a goal for Fearghal McMahon.
Mark Gottsche made a wonderful catch at centerfield and powered forward, with Monaghan native McMahon combining with Ryan Elliott to net from close range.
That left London trailing by 1-10 to 1-3 at the interval and they threatened a comeback with three points in two minutes after the restart.
However, the black-carding of Mark Gottsche knocked the wind out of their sails as Sligo began to dominate the London kick-outs, and manager Cathal Corey’s smart use of the bench saw his substitutes expose London’s tiring defence in the final quarter.
Sean Carrabine and Stephen Coen both made impressive cameos, scoring two points apiece as Sligo cruised to a 10-point victory.
London: G McEvoy; P Butler, C Dunne, D Carrabine; M Walsh, M Mangan, P Begley; A McDermott, M Gottsche (0-01); A Moyles, L Gavaghan (0-05, 0-02f), T Waters; R Elliott (0-01), F McMahon (1-01), K Butler.
Subs: L Irwin (0-02, 0-01f) for K Butler (ht), C Murphy for Moyles (ht), M Carroll for Gottsche (39, black card), C O’Neill for Dunne (43, black card), G Byrne for Walsh (53), E Murray (0-01) for D. Carrabine (63).
Sligo: A Devaney (0-01, 0-01f); R Donovan, E McHugh (0-01_, C Harrison; G O’Kelly-Lynch, A McIntyre, N Ewing; K McDonnell, N Murphy (0-02); C Henry (0-03), P O’Connor, P Hughes (0-01); L Gaughan (0-01), A Marren (1-06, 1-00 pen, 0-01f), K Cawley.
Subs: C Breheny (0-01) for O’Connor (45), S Carrabine (0-02) for Hughes (45), S Coen (0-02) for Cawley (53), F Cawley for Henry (66), D Cummins for Murphy (70).
Referee: B Cassidy (Doire).