McGregor, the first simultaneous dual-weight champion in UFC history, last fought in January, when he stopped Donald ‘Cowboy’ Cerrone in just 40 seconds.
The Irishman said he intended for that contest to be the first of a 2020 “season” consisting of three fights, but he has not stepped into the Octagon since, announcing his retirement from MMA earlier this year before last week saying he would be boxing Manny Pacquiao in the Middle East in his next bout.
McGregor, 32, boxed Floyd Mayweather in 2017 and was defeated by the American via TKO in the tenth round. Shortly after, talk of a match-up against Pacquiao began, re-emerging at intervals ever since.
But McGregor has now taken to Twitter to call out Poirier, whom he knocked out in the first round when the pair fought in the UFC in 2014.
“Hey bro! You want to do an MMA charity fight?” the Irishman wrote to Poirier, a former UFC interim lightweight champion, on Twitter.
"Zero to do with the ufc. I will donate half a [million] towards your charity for it. Sell it on ppv or work a tv deal and we work out other charities that are close to my heart also. I am engaged in many.
“Strictly a charity ‘exhibition’. December 12th in the Point depot, Ireland. No weigh ins. Open weight, unified rules. I will arrange all travel fare for you and family. McGregor Sports and Entertainment MMA, in association with The Good Fight Foundation [Poirier’s charity]. Charity Mixed Martial Arts!"
Poirier replied: “I'm in! Lets do it! A lot of people will benefit from this.”
“Excellent! We shall take it offline and progress the process from here,” McGregor then wrote.
“Good man Dustin! I respect your philanthropic efforts greatly, as well as how you conducted yourself post our first fight. You have my respect!”
The exchange took place on Monday 28 September – one day after the sixth anniversary of the pair’s UFC clash.
It is unclear whether their contracts with the UFC would allow an ‘exhibition’ bout to take place.
McGregor last week leaked messages between himself and UFC president Dana White in order to prove that his recent absence from the Octagon has not been due to a lack of desire to fight.
Following last weekend’s UFC 253 on ‘Fight Island’ in Abu Dhabi, White accused McGregor of breaking “man code” by sharing the messages on social media.