The non-league club came agonisingly close to one of the biggest upsets in the history of football's oldest competition, but still exited with their heads held high after a heroic performance.
Hosting a Premier League team ranked 115 places above them in the pyramid, few would have given Kiddy a chance of an FA Cup giant killing, but West Ham did not look prepared for the battle coming their way at Aggborough Stadium.
The atmosphere before kick-off was rapturous but the 6,000 capacity ground erupted when Alex Penny gave the hosts a remarkable lead after a goalkeeper blunder - poaching in the area to slam the ball home.
From the level of play on show in that first-half, nobody would have said it was a top flight team in action and West Ham boss David Moyes made an unwanted but completely necessary change to bring captain Declan Rice off the bench at the start of the second-half.
The 23-year-old changed the game, as you'd expect an England international who started the Euro 2020 final would, and he grabbed his team by the scruff of the neck to literally get them over the line.
After 90 where Kidderminster had not only held on but at times looked the better team, they were twice hit by an injury-time sucker punch.
The minnows were seconds away from what would have been a famous victory when Rice bounded forward as the clock ticked into three added minutes and forced extra-time with a stunning solo goal.
Then, with Kiddy seconds away from forcing a penalty shoot-out after another 30 minutes of battling, Jarrod Bowen - the most productive Englishman in the Premier League this season - struck in extra-time injury-time to leave Harriers players devastated.
However, the reaction of the home fans was not as you'd expect. There were tears, sunk shoulders and foul-mouthed mutterings, for sure, but that was quickly followed by a rousing reception for the home team.
The scenes at full-time left talkSPORT's commentary team in awe, with even former West Ham star Alvin Martin gutted for the non-league team who had come so close to making history.
"I don't know who wrote this script, but he didn't have a heart, that's for sure," said the talkSPORT pundit.
"Even as an ex-West Ham player I do feel a tremendous amount of sympathy for them, but they walk off this pitch with their heads held high."
"I've seen something today I don't think I've ever seen before," remarked Adrian Durham.
"As soon as that Bowen goal went in, every single Kidderminster fan was on their feet applauding their own team. I dont think I've ever seen anything like that at a football match."
"West Ham won the tie, but Kidderminster Harriers have won the day and the hearts of everybody in here, and probably the nation," added commentator Sam Matterface.
"They were on the verge of the greatest shock in FA Cup history - 28 years ago they shocked the world by getting to the fifth round of the FA Cup, they were so close to doing that again.
"But they will stand up and be proud of what they achieved here. They showed brilliant resilience and determination to go this far and unfortunately for them, they are out."
Former Hammer Martin was almost speechless after the match and offered his highest praise for the Kidderminster players who punched well above their weight in a superb tie.
"They didn't deserve to lose that game, but if there's a way to exit the FA Cup, Kidderminster have just shown us the way," he added.
"You walk off the pitch with the crowd cheering you, with your heads held high, having made your manager and chairman very proud.
"They're doing a lap of honour and they're fully deserving of the reception they're getting. They've raised a lot of money for the club, they've raised the profile of the club and they've put this club on the map in a different way.
"West Ham knew this team was going to give them a game, but they could not have envisaged this level of performance.
"It was up there with one of the best performances the competition has ever seen."