McGregor has endorsement deals with Beats by Dre, Monster Energy, Reebok and Bud Light. As of 2017, his endorsement deals rounded up to $7 million. In early 2018, McGregor signed a deal with Burger King.
In September 2018, McGregor launched Proper No. Twelve Irish whiskey in Ireland and the United States. The whiskey is named after the Crumlin neighbourhood in Dublin 12, in which McGregor grew up. McGregor is the founder and owner of the company.
In late 2018, McGregor said that the brand had sold "hundreds of thousands" of bottles since the launch, and plans were to restock in the United States and Ireland in December 2018. McGregor confirmed the brand will extend distribution to the UK, Australia, New Zealand, Russia, and Canada in 2019.
On 3 April 2018, Khabib Nurmagomedov and Artem Lobov had a minor altercation, in which Nurmagomedov cornered Lobov. Lobov is known to be close to McGregor, with whom Nurmagomedov has had altercations and trash talk exchanges. The two groups have a lengthy history of insults and confrontations.
On 5 April 2018, during promotional appearances for UFC 223, McGregor and a group of about twenty others were let into the Barclays Center by credentialed members of his promotional team. They attempted to confront Nurmagomedov, who was on a bus leaving the arena with "red corner" fighters for UFC 223 on it, such as Rose Namajunas, Al Iaquinta, Karolina Kowalkiewicz, Ray Borg, and Michael Chiesa. McGregor ran up alongside the slowly moving bus and then ran past it to grab a metal equipment dolly, which he then threw at the bus's window, before trying to throw other objects in the vicinity. Chiesa and Borg were injured by the shattered glass and sent to hospital. They were soon removed from the card on the advice of the NYSAC and the UFC's medical team. Lobov was also pulled from his fight for his involvement in the dispute.
Dana White said there was a warrant out for McGregor's arrest, and the NYPD said McGregor was a person of interest. White said McGregor had told him via text message: "This had to be done." "You can imagine he's going to be sued beyond belief," White said, and denied suggestions that the violence was a publicity stunt intended to generate interest in the UFC. McGregor and others involved initially fled the Barclays Center after the incident, although he and a fellow accused turned themselves in that night. McGregor was charged with three counts of assault and one count of criminal mischief. He was further charged with menacing and reckless endangerment at his arraignment and released on $50,000 bail until 14 June 2018. Under the bail conditions negotiated by his then attorney, Jim Walden, and set by the judge, McGregor was allowed to travel without restriction. On 12 April 2018, McGregor hired lawyer Bruce Mafeo of Cozen O'Connor to represent him in this matter. McGregor pleaded no contest to a count of disorderly conduct and was ordered to perform five days of community service and attend anger management classes. On 12 September 2018, Chiesa announced a lawsuit against McGregor, saying that he "experienced pain, suffering and a loss of enjoyment of life" as a result of the attack.
Following the fight at UFC 229 on 6 October 2018, Khabib Nurmagomedov jumped out of the cage and charged towards McGregor's training partner Dillon Danis. Soon afterwards, McGregor and Abubakar Nurmagomedov, Khabib's cousin, also attempted to exit the octagon, but a scuffle broke out after McGregor punched Abubakar, who then punched him back. Two of Nurmagomedov's cornermen retaliated: Esed Emiragaev and Zubaira Tukhugov, who was scheduled to fight on 27 October 2018 at UFC Fight Night: Volkan vs. Smith against Artem Lobov, the McGregor team member who was confronted by Nurmagomedov in April 2018. Nurmagomedov's payment for the fight was withheld by the Nevada State Athletic Commission (NSAC) as a result, pending an investigation into his actions. Nurmagomedov appeared at the post-fight interview and apologised to the NSAC, while also saying that, "You cannot talk about religion. You cannot talk about nation. Guys, you cannot talk about these things. This is very important to me."
The NSAC filed a formal complaint against both McGregor and Nurmagomedov and on 24 October, the NSAC voted to approve a motion to release half of Nurmagomedov's $2 million fight payout immediately. Both Nurmagomedov and McGregor received indefinite bans, at least until the official hearing, which took place in December 2018. On 29 January 2019, the NSAC announced a six-month suspension for McGregor, (retroactive to 6 October 2018) and a $50,000 fine. He became eligible to compete again on 6 April 2019.