The game began, as it would continue for much of the first-half, with Amps retaining possession for long periods.
Six minutes were on the clock before Coventry touched the ball but despite having the better of territory A’s were unable to cross the whitewash.
Coventry were reduced to breakouts from deep in their half which the hosts contained until the 36th minute, when the visitors took advantage of a turnover and hooker Scott Tolmie crashed over from close range, Will Maisey adding the extras to leave the score 7-0 at half-time.
Straight from the restart Coventry were penalised at a breakdown and James Pritchard slotted the 41st minute penalty goal.
Just four minutes later Coventry were penalised again and Pritchard struck the ball cleanly between the posts to make it 7-6.
Discipline became a significant factor as Coventry got on the wrong side of the referee.
The 57th minute saw Maisey slot a penalty which was quickly cancelled out by Pritchard on 61 minutes.
The restart was recovered by Amps and a superb break from inside their 22 resulted in flanker Joe Bercis recording his 13th try of the season on 63 minutes, Pritchard’s conversion sliding past the post.
Trailing for the first time Coventry became a touch fractious resulting in two yellow cards in close succession sandwiching a fine forwards’ try from Amps replacement prop George Thornton who crashed over from a goal-line ruck on 70 minutes for an unconverted try.
With a nine-point lead and a two-man advantage, A’s were able to see out the remainder of the game, even extending it on 78 minutes with another Pritchard penalty to make it 22-10.
Ampthill director of rugby Mark Lavery said: “It’s not often that David beats Goliath or a Town beats a City, the week went well and I thought we responded to last weeks disappointment in the right way.
“The starting team did a great job to turn round at half time 7-0 down after playing up the hill and against the breeze.
“The bench were simply magnificent and really took the game to Coventry.
“We were a little surprised that a club with Coventry’s resources couldn’t put a second team out but I guess it’s the end of the season and we are all carrying a lot of injuries.”
Head coach Paul Turner added: “After our cave-in at Butts Arena before Christmas this was always a game firmly in our sights.
“To a man the team and the bench were outstanding.
“We followed our game plan and although behind at half time stuck at it. The players deserve huge credit for beating a team as good as Coventry, we wish them the best of luck in the Championship next season.”
This Saturday Amps travel to Hull Ionians.