"At the direction of the President, the Department of State has secured the release of Otto Warmbier from North Korea," Mr Tillerson said in a statement. "Mr Warmbier is en route to the US where he will be reunited with his family."
The statement offered no other details and made no mention of former basketball player Dennis Rodman's visit to Pyongyang.
But it noted that the State Department is continuing "to have discussions" with North Korea about the release of other American citizens who are jailed there. Rodman had said he did not plan to raise the fate of the Americans while he was in North Korea.
The statement said the department would have no further comment on Mr Warmbier, citing privacy concerns.
In March 2016, North Korea's highest court sentenced Mr Warmbier to 15 years in prison with hard labour for subversion as he tearfully confessed that he had tried to steal a propaganda banner.
Mr Warmbier, 22, a University of Virginia undergraduate, was convicted and sentenced in a one-hour trial in North Korea's Supreme Court.
The US government condemned the sentence and accused North Korea of using such American detainees as political pawns.
The court held that Mr Warmbier had committed a crime "pursuant to the US government's hostile policy toward (the North), in a bid to impair the unity of its people after entering it as a tourist".
North Korea regularly accuses Washington and Seoul of sending spies to overthrow its government to enable the US-backed South Korean government to take control of the Korean Peninsula.
Before his trial, Mr Warmbier had said he tried to steal a propaganda banner as a trophy for an acquaintance who wanted to hang it in her church.
That would be grounds in North Korea for a subversion charge. He identified the church as Friendship United Methodist Church. Meshach Kanyion, pastor of the church in Wyoming, declined to comment on Wednesday.
North Korea announced Mr Warmbier's arrest in late January 2016, saying he committed an anti-state crime with "the tacit connivance of the US government and under its manipulation."
Mr Warmbier had been staying at the Yanggakdo International Hotel. It is common for sections of tourist hotels to be reserved for North Korean staff and off-limits to foreigners.
In a tearful statement made before his trial, Mr Warmbier told a gathering of reporters in Pyongyang he was offered a used car worth 10,000 dollars if he could get a propaganda banner and was also told that if he was detained and did not return, 200,000 dollars would be paid to his mother in the form of a charitable donation.
Mr Warmbier said he accepted the offer because his family was "suffering from very severe financial difficulties".
Mr Warmbier also said he had been encouraged by the university's "Z Society", which he said he was trying to join. The magazine of the university's alumni association describes the Z Society as a "semi-secret ring society" founded in 1892 that conducts philanthropy, puts on honorary dinners and grants academic awards.
In the past, North Korea has held out until senior US officials or statesmen came to personally bail out detainees, all the way up to former president Bill Clinton, whose visit in 2009 secured the freedom of American journalists Euna Lee and Laura Ling.
In November 2014, US spy chief James Clapper went to Pyongyang to bring home Matthew Miller, who had ripped up his visa when entering the country and was serving a six-year sentence on an espionage charge, and Korean-American missionary Kenneth Bae, who had been sentenced to 15 years for alleged anti-government activities.
Jeffrey Fowle, another US tourist from Ohio detained for six months at about the same time as Miller, was released just before that and sent home on a US government plane.
Mr Fowle left a Bible in a local club hoping a North Korean would find it, which is considered a criminal offence in North Korea.
