The Irish Air Corps plane carrying Daniel Kinahan, 49, landed at an airport on the outskirts of Dublin on Sunday evening after courts in Dubai refused to block his extradition.
Kinahan was taken to the Special Criminal Court in Dublin, where he was charged with directing the activities of a criminal organisation.
He was ordered to remain in custody at the high-security Portlaoise Prison about 145km southwest of the capital. His next court appearance is scheduled for October 5.
Ireland's Special Criminal Court handles all organised crime and terrorism cases, as well as others where prosecutors believe the ordinary courts are inadequate to ensure the "effective administration of justice." Cases are heard by a panel of three judges without a jury.
Irish media reported that a huge security operation was underway to ensure Kinahan faces justice.
It includes armed police, members of the armed forces and the prison service — which recently acquired a bombproof escort van to transport organised crime suspects, terrorists and other high-risk prisoners, Irish broadcaster RTE reported.
The security precautions come after Kinahan family members were linked to a bloody gang war with another Irish organised crime group.
Authorities said in 2022 that the feud had resulted in 18 murders as they announced a reward of up to $US5 million ($A7.1 million) for information leading to the disruption of the Kinahan organisation or the arrest and conviction of Daniel Kinahan.
"Since February 2016, the (Kinahan Organised Crime Group) has been involved in a gang war with another group in Ireland and Spain, resulting in numerous murders, including of two innocent bystanders," the US Treasury Department said when it sanctioned six members of the Kinahan gang and three businesses linked to it.
Irish police, with the help of authorities in Britain, Spain and the US, have been pursuing members of the Kinahan gang since at least 2016, when the feud led to a daytime shooting during the weigh-in for a boxing match at a Dublin hotel. Kinahan was a boxing promoter at the time.
The authorities allege the gang smuggled tens of millions of dollars in illegal drugs, including cocaine and cannabis, as well as guns into Europe, then used a network of apparently legitimate enterprises to launder the profits.
Kinahan is believed to have run the day-to-day operations of the gang from his base in Dubai, the US Treasury said.
That includes buying "large quantities of cocaine" from South America, organising its distribution in Ireland and attempting to smuggle drugs into the UK, the US Treasury said.
Kinahan has also instructed gang members to deliver money to a number of people in prison, including one who was convicted of attempting to murder someone on behalf of the organisation, the agency said.
He was detained by Dubai authorities in April on an Irish arrest warrant.
During a phone interview with Scottish podcaster James English last week, Kinahan denied being an organised crime boss and described himself as the victim of a conspiracy to tarnish his reputation.
While he said the extradition proceedings were expedited due to a deal between the Irish and Dubai governments, he said he hoped his trial in Dublin would help clear his name.
"I believe, in a way, I am a scapegoat," he said in the interview posted on TikTok.
