Callum Morton struck a brace and Vadaine Oliver was likewise on target.
Northampton conquered a 2-goal first- leg deficit to declare their location in the League 2 play- off final following a 3-0 win at Cheltenham.
Goals from Vadaine Oliver and Callum Morton carried them level on aggregate at 2-2 prior to Morton, on loan from West Brom, bagged the winner 13 minutes from time.
The visitors looked the livelier throughout and threatened as early as the 4th minute when Nicky Adams‘ cross from the left discovered Morton however his header did not have the speed to problem Robins goalkeeper Owen Evans
An early corner and a number of long tosses from skipper Charlie Goode put the home defence under more pressure prior to the Cobblers made their early pressure count with their ninth-minute opener.
Adams once again supplied the cross, this time from the right, and Oliver increased on the edge of the six-yard box to direct his header past the Cheltenham keeper and into the bottom right-hand corner.
When Morton developed space for the shot however skied his effort over the bar,
There was practically a second a minute later on.
The visitors were practically captured out on the half- hour when a long clearance from Evans selected Ryan Broom, who in turn played in Alfie May however the striker was offside.
Jonte Smith put an effort a backyard broad of the Cheltenham target as the hosts wanted to level on the night and they were granted their first corner 8 minutes prior to the break just for Jake Doyle-Hayes‘ kick to be headed clear.
Both sides went close late in the half, Oliver climbing up high to head a wonderful Goode changeover the target for the Cobblers while at the other end, May had actually an effort obstructed by the hard-working Northampton skipper.
Cheltenham boss Michael Duff sent out on striker Reuben Reid at the start of the second half in location of Smith and the home side had an early effort when Doyle-Hayes put in a low shot.
However this was to be a false dawn for the Robins. Minutes later on Oliver stung the palms of Evans prior to Adams put an effort inches broad with the Cheltenham keeper beaten.
The equaliser followed 57 minutes when Goode got his head on an Adams corner and Ben Tozer‘s tried headed clearance for the hosts rebounded off Morton into the net.
Another corner soon after saw Scott Wharton head over as the visitors wanted to cover things up however it was an error that talented them their winner with 14 minutes staying.
A mix-up in between keeper Evans and defender Will Boyle permitted the ball to run for Michael Harriman His shot struck the foot of the post however Morton followed up for his second of the game.
The young striker practically concluded his hat-trick when, with 7 minutes staying, he broke upfield just for Evans to stay out his final shot.
Cheltenham promoted an equaliser in the 7 added minutes at the end however the visitors hung on for the win.