Saints have opted to switch their home league fixture against Leicester Tigers to Twickenham to raise funds for Rob Horne.
The Australian centre was forced to retire after less than a season at Northampton after sustaining full paralysis to his right arm.
That injury came inside the first minute of the victory against Tigers at Welford Road on April 14.
Horne, who was captaining the club for the first time during the derby-day clash, was named Saints' supporters' and players' player of the year at the end-of-season dinner.
He was the club's top try scorer during the 2017/18 campaign, registering eight efforts in just 21 games following last summer's move from Super Rugby side the Waratahs.
And everyone at Saints has been keen to honour his stay properly since news emerged that he would not be able to play again.
Now it has been decided that the Gallagher Premiership fixture against Tigers on October 6 (kick-off 3pm) will move from Franklin's Gardens to Twickenham.
Saints will donate £5 on behalf of every season ticket holder, while supporters will have the option to make a contribution as they purchase tickets.
There will also be a number of fundraising opportunities on the day itself, with donations going towards Horne's ongoing rehabilitation and ensuring some financial security for the 28-year-old and his family.
“The outpouring of support for Rob at the end of last season from the whole rugby community in the east midlands was overwhelming – and we wanted to act,” said Saints chairman John White.
“The club received countless requests from both Saints and Tigers supporters for a fitting way in which they could both bid farewell to Rob and also support him.
“Leicester Tigers’ chairman and board have also made it clear that they are very keen to help Rob in any way they can, and this is a superb way to do that.”
The RFU approached Saints to host a home match at Twickenham earlier this summer so they could test their new east stand development ahead of the 2018 autumn internationals.
And Saints chief executive Mark Darbon admits the opportunity was an incredibly exciting one for the entire club.
“We were asked to help test the new east stand redevelopment because of our fantastic supporter base and the size of this game – the east midlands derby is undeniably the biggest fixture in English club rugby," Darbon said.
“There was a significant financial incentive for the club to host the game – one we could not ignore – which enables us to maximise the funds we can raise for Rob.
“This is also a unique opportunity for Saints supporters to experience the brand-new Twickenham east stand development before anyone else.
"I hope it’s a great day out for them at the home of English rugby.”
The club’s season ticket holders will have prime seating reserved at Twickenham, as well as a free alcoholic or non-alcoholic beverage up until 2pm.
Free coaches will be laid on to allow season ticket holders to easily get down to London, while other travel packages will be available for supporters travelling down from Northampton for the day.
Horne will be returning to the UK to attend the fixture and deliver the match ball in October after moving home to Australia with his family last week.
And Chris Boyd, Saints' new director of rugby, said: “This is a great opportunity for the club and a great chance for the rugby family to get behind Rob.
“I’m sure the playing squad are all looking forward to playing the derby on one of the biggest stages in the world at Twickenham – no doubt our supporters will create the same special atmosphere we have in Northampton down in London to get behind us.”
Ticket prices start from £20 for adults and £10 for juniors.