Louth 2-17 Monaghan 1-13
Diarmuid Murphy scored nine points as Louth advanced to the Nicky Rackard Cup final at Croke Park on Saturday, June 4.
Second half goals from Shane Callan and Donagh O'Sullivan were also vital, helping Louth erase an early 0-08 to 0-03 deficit.
Monaghan were firmly in command in the opening stages with Michael McHugh (0-02), Stephen Lambe, Trevor Hillard, Sean Leonard, Eanna MacSuibhne, Brian McGuigan and Gary Boyd helping the hosts claim a five-point advantage.
Indeed, five of Monaghan's starting six forwards registered scores inside the opening 20 minutes of this well-contested tie.
Louth kept in touch thanks to the efforts of Murphy, with a Brian Corcoran point leaving the scoreline at 0-08 to 0-04 in the 26th minute.
Midfielder Boyd restored Monaghan's five-point lead a minute later, but his side failed to score over the remainder of the half.
Louth were strongest in the closing stages, Corcoran, Murphy (0-02) and O'Sullivan all firing over points to cut the cap to the minimum.
The Wee County side were unlucky not to take the lead by half-time. O'Sullivan was denied a 29th minute goal after some solid defending by Monaghan.
Louth doubled their advantage with four unanswered points inside 14 minutes of the restart. Callan tied the contest immediately after the restart, before a trio of Murphy scores gave the visitors a 0-12 to 0-09 lead by the 48th minute.
Monaghan rued three missed scoring opportunities from McHugh during this period, while Boyd also sent an effort wide of the posts. Lambe helped inspire a Monaghan comeback, but the free-taker failed to put his side in front.
Lambe claimed three of the next four points, but Callan's goal from a pass from Murphy gave Louth a decent cushion - they were seven points clear with just four minutes of normal time left.
Monaghan immediately responded with Lambe netting a goal from the resulting puckout, but Louth substitute Wesley Morrissey steadied the ship with two points.
Louth sealed the win with a fortuitous goal from O'Sullivan deep into injury-time. He drilled a low shot into the right corner past Monaghan goalkeeper Hugh Byrne.
Scorers - Louth: D Murphy 0-09, B Corcoran 0-03, D O'Sullivan, S Callan 1-01 each, W Morrissey 0-02, G Smyth 0-01
Monaghan: S Lambe 1-05, M McHugh, G Boyd 0-02 each, T Hillard, B McGuigan, E MacSuibhne, S Leonard 0-01 each