The 27-year-old has been the subject of interest from a number of third and fourth-tier clubs over the last month, but appeared set to stay at Wetherby Road until at least January.
Sulphurites boss Simon Weaver had insisted that Armstrong would only be allowed to leave for a “significant” transfer fee - reportedly in the region of £500,000 - and if the club had a like-for-like replacement lined up.
Until Friday, none of the interested parties had got close to meeting Harrogate’s asking price, with Weaver stating on Wednesday that he didn’t expect any movement because "we haven’t managed to get a replacement in.”
But, just hours before the summer transfer window slammed shut, Wrexham managed to tempt the North Yorkshire outfit into doing business, trumping a reported £375,000 offer from fellow League Two side, MK Dons.
The exact sum paid by the Red Dragons for Armstrong’s services will remain undisclosed.
“We have reluctantly decided that Luke can go to another club,” Weaver said.
“It has taken its time because we wanted to keep him. He’s been a great player for the club and we wanted to look after the club and get a good fee in, and we’ve managed to do that, but we wish him well.
“He’s been fantastic and I’m glad for him that he’s got back to enjoying his football at Harrogate Town. In some ways it’s a feather in our cap that a player has enjoyed it so much and felt freed up.
“I think it’s a winning situation for him and for the club because we’ve got a really good fee.
“When a player says ‘I want to go and my heart is elsewhere’, then you have to take it seriously and consider the effect it might have on the team and himself should it not go his way. So, in the background, we have been working really hard on bringing in centre-forwards.”
Armstrong signed for Harrogate from Salford City in the summer of 2021.
He scored 14 times in his first season at Wetherby Road and went on to enjoy an even better year in front of goal last term, finding the net on 16 occasions as he started every single one of Town’s 46 League Two fixtures
The former Middlesbrough forward bagged his first and only goal of the current campaign in last Saturday’s 2-0 home win over Morecambe, converting a 20th-minute penalty.
But that strike only came after he missed Town’s opening two matches of 2023/24 having said that he wasn’t in the right frame of mind to play amidst a flurry of transfer bids lodged by League One and Two sides on the eve of the new season.
Despite still having two years to run on his contract, Armstrong was offered a three-year deal on improved terms earlier this month but could not be persuaded to sign it.
He departs the EnviroVent Stadium having made 106 competitive appearances for the club in total, scoring 31 times and contributing 12 assists.