The westerners led from the gun and won pulling up, two goals by full-forward David O’Gara key to victory.
Wind-aided Roscommon careered into an early 0-4 to 0-0 lead, corner-forward Donie Smith’s three frees helping them on their way.
Cavan hit back in the 10th minute when Martin Dunne goaled against the run of play from the penalty spot after Eugene Keating was fouled.
Cavan huffed and puffed in playing catch-up but points from Niall McDermott (free) and Martin Reilly helped close the gap to a point (1-3 to 0-7) on the half-hour.
However, the Rossies hit the hosts with a real sucker punch when O’Gara goaled in the 33rd minute to open a 1-7 to 1-3 half-time lead.
Cavan’s error-ridden play was repeated in the second-half with their lateral play and failure to use the elements helping to undo their cause. Points from Eugene Keating and Cian Mackey sandwiched yet another Smith free (42) for Roscommon as the play swung from one end of the field to the other with abandon. Roscommon sub Donal Keane and half-back David Keenan heaped on the misery as the visitors ran riot.
Cavan introduced totemic midfielder David Givney on the hour mark but it mattered little as moments later O’Gara pounced for his second goal of the day.
CAVAN: J Reilly; K Brady, P Reilly, R Flanagan; R Dunne, J McEnroe, J McCutcheon; G McKiernan (0-2), D McKiernan; M Reilly (0-2, 1f), C Mackey (0-1), M McKeever; M Dunne (1-0 pen), N McDermott (0-1f), E Keating (0-1).
Subs: K Meehan for J McCutcheon (half-time); K Tierney for M Dunne (49); B Reilly for M Reilly (51); O Minagh for P Reilly (55); D Givney for M McKeever (61).
ROSCOMMON: D O’Malley; N Collins, N Carty, S McDermott; D Keenan (0-1), S Purcell, I Kilbride; M Finneran, K Higgins (0-1); C Dineen, K Mannion (0-1), C Cregg (0-3, 2f); D Smith (0-6, 6 f), D O’Gara (2-0), D McDermott.
Subs: D Keane (0-1) for C Dineen (half-time); P Brogan for S Purcell (half-time); S Oates for D McDermott (42); E Smith (0-1) for D Smith (62); D Butler for C Cregg)
Referee: F Kelly (Longford).