Longford established early control but Carlow stayed in touch and John Murphy’s superb 29th minute goal gave Turlough O’Brien’s men hope as they trailed 0-12 to 1-6 at the break.
The midlanders scored the opening four points of the second half but Carlow responded with four unanswered white flags of their own.
But any prospect of a shock result was scotched when Longford substitute Dessie Reynolds scored his side’s goal in the 56th minute for a 1-16 to 1-11 lead and they went on to record a comfortable win.
B Kavanagh 0-6, 0-3 frees, R McNerney 0-5, 0-2 frees, D Reynolds 1-0, M Quinn, P Gill 0-2 each, B Gilleran, L Connerton, S Doyle 0-1 each.
J Murphy 1-1, S Gannon 0-3, E McCormack 0-2, both frees, B Murphy (free), D St Ledger, A Kelly, D Foley, C Moran, D O’Brien 0-1 each.
G Higgins; F Battrim, T Gallagher, B Devine; A Rowan, C Farrelly, D Brady; B Gilleran, C Quaine; S Doyle, M Quinn, P Gill; R NcNerney, B Kavanagh, L Connerton.
P McKeon for Gilleran (46); D Reynolds for Doyle (50); R McIntyre for Gill (53); B O’Farrell for Brady (61); R Conor for Rowan (63); F McGee for Quaine (injured) (66).
R Molloy; B J Molloy, S Redmond, K Nolan; M Fitzgerald, D St Ledger, B Kavanagh; S Gannon, D Foley; A Kelly, J Murphy, D Hayden; E Finnegan, B Murphy, D O’Brien.
D Kelly for Kavanagh (injured) (27); C Moran for Finnegan (47); D Moran for Fitzgerald (47); H Gahan for Foley (48); E McCormack for B Murphy (48); M Meaney for J Murphy (63).
J Bermingham (Cork).