Champion UFC fighter Conor McGregor has announced he is retiring from mixed martial arts.

McGregor, who previously retired from the sport shortly following his loss to Nate Diaz in 2016 before returning to face down Diaz last year, took to Twitter to announce his decision.

"Hey guys quick announcement, I've decided to retire from the sport formerly known as "Mixed Martial Art" today," McGregor shared on Twitter. "I wish all my old colleagues well going forward in competition."

Hey guys quick announcement, I’ve decided to retire from the sport formally known as “Mixed Martial Art” today.
I wish all my old colleagues well going forward in competition.
I now join my former partners on this venture, already in retirement.
Proper Pina Coladas on me fellas!

— Conor McGregor (@TheNotoriousMMA) March 26, 2019

McGregor, who made his MMA debut in 2008 and joined the UFC in 2013, completes his career with a 21-4 record. The 30-year-old fighter turned in many memorable performances over his career, including his knockout of Jose Aldo to secure the featherweight champion title in 2015 and his win against Eddie Alvarez to snag the lightweight champion title.

During a hiatus, McGregor took on Floyd Mayweather Jr. in Las Vegas in "The Money Fight". Mayweather defeated McGregor by technical knockout in the 10th round and extended his undefeated streak to 50 wins.

McGregor has had run-ins with the law in the past, including an arrest earlier this month following an altercation with a fan. Last year, he was charged with assault and criminal mischief after throwing a metal hand cart at a UFC bus in Brooklyn.