By Vanessa Brown
On Sunday, boxing champion Floyd Mayweather outclassed McGregor to win their money-spinning superfight by technical knockout in the 10th round.
But while McGregor didn't walk away from the ring with a win - the Irish mixed martial arts star says none of his successes to date would be possible without the support of his longtime girlfriend - and mother of his son - Dee Devlin.
From humble beginnings, Ireland-born Devlin has remained the consistent rock in McGregor's life, reports News.com.au.
The 30-year-old brunette has stood by McGregor throughout his challenging career, even before he stepped in to the spotlight.
"My girlfriend worked very hard throughout the years and stuck by me when I had essentially nothing," he told the Irish Mirror.
"For me to be able to take her out of work, give her everything she's ever wanted and to travel the world with, fills me with pride."
Before his worldwide success, fame and millions of dollars in prize money and endorsements - the love story between McGregor and Ms Devlin started at an Irish nightclub in 2008, where the brunette beauty revealed how sparks flew at first sight.
"He's very funny - he always keeps me entertained and makes me laugh," she told VIP Magazine.
"He was already training when I met him, so I really admired his dedication to that, too."
McGregor admitted that is was Ms Devlin's "good girl" qualities that attracted him to her in the early stages.
"I asked her to come over and we just started chatting. She seemed like a nice girl, and I like good girls."
But her dedication, commitment and selflessness is what enabled the pair to last almost a decade together.
"Every day, since I started out in this game, she's supported me," he said.
"She'd drive me to the gym, and she'd listen to all my dreams. Dee is a lifesaver for me. I wouldn't be doing this if it wasn't for her, and that's for sure. I'm doing all of this for her."
Following the bout in Las Vegas over the weekend, Devlin took to Instagram to share a snap with her partner and son, along with McGregor's mum Margaret, dad Tony and two sisters Erin and Aoife.
Devlin captioned the family snap with a simple love heart emoji as UFC star McGregor smiled as he held his baby son, Conor Jack Jr, in his arms.
Devlin and the couple's baby boy - who have been in Las Vegas with McGregor as he geared up for the megafight - jetted to London to celebrate McGregor's 29th birthday during the promotional tour for the fight.
In 2015, after his stellar win against Chad Mendes in Las Vegas - Ms Devlin posted an emotional tribute to her partner.
"To say that I am proud is a MAJOR understatement!" her Instagram post read.
"I am so on cloud 9 right now I can't even put it into words! Thank you to every single person who made the trip out to Vegas to support Conor last night!
"The place was absolutely buzzin! And to all of the fans at home who also had a big part to play in making this event so special.
"Hours upon hours, years upon years of hard work and complete dedication to his craft accumulated last night.
"I am so grateful right now it's overwhelming. We did it babe! I love you more than anything."
In an interview with ESPN, the Walkinstown native explained how she takes care of everything outside of the fight - so McGregor can simply concentrate on the task at hand.
"I definitely try to help him out all the time, even without realising it - especially around a fight because it's such a tough time with his weight," she said.
"I cook, clean, pack his gym bag, all that kind of stuff."
McGregor has been vocal in the past about his appreciation and commitment to Ms Devlin, who has supported him from the days of "absolute nothing".
In an interview with the Sunday Independent, McGregor's coach - John Kavanagh - explained how he come from a life on the dole, and living week to week on social security checks.
"It wasn't easy. Conor was on the dole, earning AU$143 a fight and training at the height of winter in a cold gym," Kavanagh said.
"Now, I don't care how passionate you are, but there are always going to be periods thinking 'F**k this! What am I doing here?
"Conor's annual earnings for that five-year period was something like €1,500 a year. There was no money and I was running out of ideas. The UFC was a closed shop."
When he's not fighting, McGregor and Devlin love to travel and shop together, and despite his rigorous training and competition schedule - spend valuable time with one another and their newborn.
"My girlfriend has been there since the start. She has helped me throughout this career," McGregor told the Irish Mirror.
"If It wasn't for her, I probably wouldn't be where I am today. So definitely, I love to spoil her."
Devlin also helps her partner by helping to manage his finances.
"She has helped me throughout this career," he told MMA Fighting in 2015. "She does not work anymore, I hired her to the business ... she works for me now and collects the checks."
Outside the arena, 'The Notorious' has several partnership deals and product endorsements - including Reebok, Bud Light, Volvo and Monster Energy.
"Sometimes it's tough but life is tough for everyone, and it will all be worth it in the end," McGregor told VIP magazine.
"I'm doing this to secure my family's future and Dee's future.
"One day, I want myself and Dee to be able to chill on a beach and not have any worry in the world.
"That's why I'm doing this. I want to be financially secure."
Speaking of his newly found celebrity and how that will be managed around his baby - McGregor said that he had no intention of bringing Conor Jack Jr up in a fame-driven world.
"I don't even know what way to take it, it's going to mess with my head because I don't want to bring a child into anything like this," he said.
"I don't want no little celebrity type sh**, I hate that. I don't want my family to be like that.
"That's a little thing that's in my head. I'm going to have this baby, take a little time and see what way I feel after that."