The Cobblers booked themselves a day out at Wembley on Sunday as they overcame Cheltenham Town 1-0 in the return leg of their semi-final clash - wrapping up a 2-0 aggregate success.
Boothroyd's side will now face Bradford City for the right to compete in the third tier next season.
He believes Northampton are fully deserving of that opportunity and is convinced they have what it takes to get over the line.
Boothroyd told Sky Sports: "We had to defend for our lives. We knew they would come at us. Cheltenham are a good team and this stage of the season you are going to get better opponents and they are going to bring the best out of you.
"I thought our goalkeeper, to be fair, was absolutely fantastic. We had to weather a storm, we did that. We didn't play anywhere near as well as we could but we got the result, and that's what counts."
Asked if he felt Northampton had been the better side over the course of the two legs, Boothroyd added: "I do, yeah. Second half at our place I thought we were outstanding and should have won by more. But they always had a chance, an opportunity with a set-play, and we had to defend very, very well. Our goalkeeper was excellent. We are delighted.
"We have worked very hard to get this far. We are all in it together and we are due a bit of good fortune and a bit of success. We will work our best, we know it's going to be difficult against a tough team, but we think we can do it."