Westmeath suffered their sixth straight defeat and their latest setback at Dr Cullen Park confirmed the Lake County's relegation.
Kevin Martin's men edged the first half against an out-of-sorts Carlow but at half-time were only on level terms at 0-8 apiece.
Westmeath were out of luck on 31 minutes when Dan Carty's fierce drive crashed off the Carlow crossbar. It was somehow cleared, thus denying the visitors a certain goal, which would have been reflective of their play.
The game turned Carlow's way early in the second half when a brace of long-range points from play by midfielder Jack Kavanagh, supplemented by another white flag from half-time substitute Andrew Gaule, sent the Barrowsiders three points clear (0-12 to 0-9).
On 49 minutes, centre- forward Eddie Byrne latched onto a ball 30 metres out, beat his man, and hammered home a superb goal.
Westmeath were not done yet, though. The impressive Ronan Whelan cracked home a goal three minutes later after Carlow 'keeper Kevin Kehoe had initially made an excellent save.
But the league points were put beyond Westmeath on 59 minutes when a fine passage of play by the home county saw impressive full-forward Eoin Nolan find the visitors' net to put Carlow into a 2-14 to 1-11 lead.
Although they never gave up, it was now a lost cause for Westmeath.
Man of the Match: Jack Kavanagh
Scorers -- Carlow: R Dunbar 0-6 (6f), E Byrne, E Nolan 1-1 each, J Kavanagh 0-2, C Clancy, J Rogers, M Brennan, P Kehoe, A Gaule 0-1 each.
Westmeath: R Whelan 1-2, A Mitchell 0-3 (2f, 1 '65'), D Carty 0-3 (2f), D McNicholas 0-2, J Shaw, E Price, C Curley, B Murtagh (pen) 0-1 each.
Carlow -- K Kehoe 7; A Corcoran 7, S Kavanagh 8, B Doyle 7; E Coady 6, D Kavanagh 6, R Coady 7; J Kavanagh 8, J Rogers 7; M Brennan 6, E Byrne 7, J Doyle 5; C Clancy 5, E Nolan 7, R Dunbar 7. Subs: P Kehoe 7 for J Doyle (h-t); A Gaule 6 for Clancy (44). Westmeath -- C Scally 6; C Flanagan 6, D McCormack 6, A McGrath 6; R Whelan 8, A Mitchell 7, P Gilsenan 6; N Flanagan 7, J Clarke 7; J Shaw 6, A Price 6, E Price 6; A Devine 5, D McNicholas 6, D Carty 7. Subs: B Murtagh 6 for Devine (35); C Curley 6 for E Price (52).
Ref -- J O'Connell (Cork).