Two ambulances met the plane on the runway to transfer Otto to the hospital.
Mr Rodman is a friend of North Korean leader Kim Jong-un and has made several visits to the country in recent years.
Last week, North Korean officials told Yun about Warmbier's medical condition.
Secretary of State Tillerson said the State Department is continuing to discuss three other detained Americans with North Korea. North Korea repatriated a sick US citizen it had held captive for 17 months, and Dennis Rodman arrived with fanfare in Pyongyang.
The announcement came amid tension between Washington and Pyongyang following a series of missile tests by the North, focusing attention on an arms buildup that Pentagon chief Jim Mattis on Monday dubbed "a clear and present danger to all". He was sentenced to 15 years in jail after tearfully confessing to trying to steal a propaganda sign.
The last time Rodman visited North Korea, he delighted the country's young ruler with a rendition of "Happy Birthday", suffered an angry meltdown on CNN while defending his trip, and spent time at a rehab facility after returning to the United States.
"Sadly, he is in a coma and we have been told he has been in that condition since March of 2016", they said.
Officials could not immediately confirm USA media reports that Warmbier had fallen into a coma during his incarceration.
"We want the world to know how we and our son have been brutalized and terrorized by the pariah regime in North Korean".
They also said they are grateful Mr Warmbier "will finally be with people who love him".
In Warmbier's hometown of Wyoming, just outside of Cincinnati, residents helped tie blue and white ribbons, Wyoming High School's colors, to trees and said news of his release had sent waves of shock and joy through the community.
"It wasn't a situation where they asked", one official said of the US representatives. Let me reiterate this: "We strongly, strongly suggest that Americans do not go to North Korea". He is scheduled to meet North Korea's sports minister before he leaves the country on Saturday.
US officials appeared to brush aside any speculation of a connection between Rodman's controversial visit and Warmbier's release.
It was a relatively low-ley arrival after his four past trips since 2013 generated a lot of publicity - most of it unfavorable - and did little in terms of diplomacy.
The announcement comes as former National Basketball Association player Dennis Rodman is paying a return visit to North Korea.
Mr. Rodman also has had a relationship with Donald Trump developed while appearing twice, in 2009 and 2013, on the latter's Celebrity Apprentice television show.
The U.S. government accuses North Korea of using such detainees as political pawns.
She said US officials had a hard time getting information about Warmbier from North Korea.
Previous detainees have been released after visits from high-profile Americans, including former presidents Jimmy Carter and Bill Clinton.
Three weeks later, North Korea announced it was holding him for a "hostile act" against the state. He was detained at Pyongyang's airport ahead of a flight to China. He was accused of committing unspecified criminal acts meant to overthrow the government. Shortly after Warmbier's sentencing, Kim Dong-chul, was arrested on accusations of espionage, and has been held ever since.
However, before his arrival in Pyongyang, Rodman told reporters that pleading to free detained Americans is not the goal of his visit right now.
"Otto has been in a coma for over a year now and urgently needs proper medical care in the United States", said Richardson, who has previously served as a special envoy to North Korea and still works on prisoner issues.
Secretary of State Rex Tillerson testifies on Capitol Hill in Washington, Tuesday, June 13, 2017, before the Senate Foreign Relations Committee.
U.S and North Korean officials say Rodman had nothing to do with the release of American student Otto Warmbier, who had been serving a 15-year sentence in a North Korean prison for alleged anti-state acts.