Stephen Kenny's side defeated the Bit o' Red by the same margin of victory as their last game at Oriel Park, reaching the FAI Ford Cup third round in the process
Goals either side of half-time put Dundalk in the driving seat as David McMillan and Daryl Horgan netted, before Brian Gartland sealed Sligo's exit with a powerful strike half-way through the second-half.
Stephen Kenny named a strong side against his Premier Division opponents, and was rewarded for that decision when they took the lead on 31 minutes. Richie Towell played in McMillan, and the striker struck against his former employers.
Two minutes into the second-half, Horgan added Dundalk's second with his fifth goal in as many games, picking up the ball from McMillan before slotting it past Gary Rogers.
Rogers had to pick the ball from the net again on 65 minutes when Gartland fired in after the goalkeeper parried McMillan's effort into his path.
McMillan could have had another late on after an impressive performance, but Stephen Kenny's side will be pleased with the victory, which sees them progress to the last 16 of the tournament.