Aijalon Mahli Gomes, 31, was sentenced to eight years’ hard labour in April, after being found guilty of illegally entering the country from China.
Mr Carter met senior North Korean officials after arriving in Pyongyang on Wednesday.
He has now left to fly back to the US with Mr Gomes, a devout Christian who had entered North Korea in January.
The state-controlled North Korean Central News Agency (KCNA) said that the North’s Deputy Prime Minister Kim Yong-nam had informed Mr Carter of his country’s willingness to return to international negotiations, known as the six-party talks.
“(Kim Yong-nam) expressed the Republic’s commitment to denuclearise the Korean peninsula and resume the six-way talks,” KCNA said.