Veteran attacker Seanie Furlong fired two crucial goals to keep Wicklow in Division 3 of the Allianz Football League, consigning reigning Ulster champions Cavan to a shock relegation.
Mickey Graham's Breffni were hot favourites to win in Navan but surprisingly played catch up for much of the game and slipped to their third consecutive relegation, meaning they will play Division 4 football in 2022.
The shock loss leaves them up against it to rescue anything from the season with an intimidating Ulster SFC quarter-final tie against Tyrone in Omagh next up on 10 July
But Davy Burke's Wicklow will march on confidently to their Leinster SFC Round 1 tie against Wexford in Aughrim on 27 June.
If they win that game they will take on Dublin and the Garden County will head into the championship high on confidence and momentum after this huge win.
Furlong was their talisman yet again up front but it was a huge team effort with eight different scorers at Pairc Tailteann and a number of players pulling up with cramp late on given the intensity of the game.
Furlong's two goals both arrived in the second-half and turned the screw on a Cavan side that simply never sparked as expected.
This was Wicklow's first season in Division 3 since 2013 and they were determined to stay there, showing their enthusiasm with an early burst of scoring.
With seven minutes on the clock they led by 0-03 to 0-00 and displayed their full range of talents with each score.
Andy Maher struck the first after a well worked passing move, Mark Kenny boomed over the second from distance and the third was a route one move, Maher picking out Patrik O'Connor with a 60-yard ball downfield.
Cavan battled back to lead by 0-04 to 0-03 after 17 minutes, Conor Madden, Patrick Lynch, Gearoid McKiernan and Conor Brady pinching the points.
But they didn't kick on as expected with their play ragged at times. All-Star Thomas Galligan did well to recycle one ball that hit the post, spinning away from his man and shooting for goal but wincing as the ball struck the bar this time.
It looked like it may be that sort of day for luckless Cavan who were rocked by Wicklow's goal two minutes later.
Podge O'Toole broke through Cavan's last line of defence with a clever hand pass over the top, allowing O'Connor to race clear and slide a low shot beneath Raymond Galligan.
Conor Smith pulled back a point for Cavan but Wicklow still deservely led 1-05 to 0-07 at half-time.
There was a brief reprieve for Cavan early in the second-half and they took the lead following points from Patrick Lynch and Thomas Galligan.
But Wicklow came roaring back again with 40th and 50th minute goals, both from Furlong.
His first came after a Cavan misjudgement at the back, Padraig Faulkner failing to deal with O'Connor's crossfield ball and Furlong capitalising with an unchecked run and superb finish.
Conor Byrne and Kevin Quinn added points before Furlong struck again, nailing Wicklow's third goal from a penalty.
Eoin Darcy was bundled over for the spot kick after a quickly taken 'mark' found him in space and now Wicklow were six points clear, 3-07 to 0-10.
Cavan pulled back eight points from there on but needed a goal which never arrived and Wicklow points from Furlong, substitute Christopher O'Brien and goalkeeper Mark Jackson got them over the line with two points to spare.
Wicklow: Mark Jackson (0-01, 0-01f); Oisin Manning, Jamie Snell, Nicky Devereux; David Devereux, JP Hurley, Niall Donnelly; Kevin Quinn (0-01), Podge O'Toole; Andy Maher (0-01), Mark Kenny (0-01), Conor Byrne (0-01); Patrick O'Connor (1-02), Seanie Furlong (2-03, 1-00 pen, 0-02f), Eoin Darcy.
Subs: Eoin Murtagh for Snell (17), Arran Murphy for O'Connor (52), Darragh Fitzgerald for A Maher (57), Christopher O'Brien (0-01) for Quinn (60), Paul Cunningham for Darcy and Dan Keane for Byrne (67).
Cavan: Raymond Galligan (0-02, 0-01f, 0-01 45); Cian Reilly, Padraig Faulkner, Killian Clarke; Cormac Timoney, Oisin Kiernan, Luke Fortune; Thomas Galligan (0-03), Conor Brady (0-01); Caoimhan McGovern, Gearoid McKiernan (0-03, 0-02f), Martin Reilly; Conor Madden (0-03, 0-01m), Patrick Lynch (0-03, 0-02f), Conor Smith (0-01).
Subs: Caoimhin O'Reilly for McGovern (28), Paddy Meade for Smith (47), Chris Conroy (0-01) for Fortune (51), Oisin Pierson (0-01) for O'Reilly (57), Sean McEvoy for Lynch (71).
Referee: Barry Judge (Sligo).