On an afternoon where a win would all-but seal a top-seven finish, the Poppies struggled to make any inroads against their mid-table hosts.
And while Kettering couldn’t find a win, former manager Paul Cox and Boston United did as their 2-0 success at Farsley Celtic sealed the final play-off place.
There could be no arguments at the final outcome at Curzon.
The hosts were the better side for long periods as Kettering never really got going in either half, despite being spurred on by a large travelling band of supporters.
They did find a late goal through Decarrey Sheriff but it was a disappointing finish after the Poppies held all the aces going into the final day.
In the long run, however, they will be able to reflect on a highly encouraging campaign which delivered more than anyone could have expected.
Kettering were the first to register an attempt on target after an even start with Callum Stead drawing a fine low save out of Chris Renshaw.
But that was as good as it got for the Poppies as they struggled to get any change out of a strong Curzon outfit.
Indeed, the hosts had the better chances in the remainder of the half with Alex Brown producing a fine block to deny Jordan Richards while Scott Wilson headed over from a good position from Richards’ delivery from the right.
The theme continued in the second half and the warning signs were there for Kettering when Tom Peers had the ball in the net, only for his effort to be ruled out for offside.
But there were no doubts on 52 minutes when Curzon took a deserved lead.
Peers threaded the ball through to Richards in the right channel and his low effort found its way in via the near post.
Ian Culverhouse threw defender Liam Daly and Ty Deacon on and switched to a 4-2-4 formation but the Poppies were still unable to create any clear-cut chances.
A fine tackle from Connor Johnson stopped Peers from making it 2-0 while the best chance at the other end fell to Connor Kennedy who could only fire over after the ball broke nicely for him on the edge of the penalty area.
That was until deep into stoppage-time when Daly headed Kennedy’s cross back in and Sheriff was there to nod home.
However, it was the final play of the game as Kettering’s hopes were dashed at the death.
Curzon Ashton: Renshaw; Challoner, Poscha, Barton, Wilson; Dimaio, Lussey (sub Nolan, 78 mins); Richards, Curran (sub Whitham, 90 mins), Mahon (sub Hobson, 83 mins); Peers. Subs not used: Rain, Gladwin.
Kettering: Jackson Smith; Barrett, Johnson, Cooper, C Smith (sub Sheriff, 58 mins), Brown; Kennedy, Stohrer, Sharpe (sub Daly, 67 mins); Crawford, Stead (sub Deacon, 67 mins). Subs not used: Davies, Jack Smith.
Referee: Richard Aspinall.
Goals: Richards (52 mins, 1-0), Sheriff (90 mins, 1-1).
Bookings: Kennedy, Barton, Johnson, Dimaio (all fouls), Cooper, Crawford (both dissent).