The North's official KCNA news agency announced their arrival in Pyongyang as "a US Google delegation headed by former governor of New Mexico Bill Richardson".
Mr Richardson, who is also a former US ambassador to the United Nations says he and Mr Schmidt would be travelling as private citizens, representing neither the US government nor Google, he said.
"This is a private humanitarian mission, not connected to the US government," he said.
"We're going to be in Pyongyang, probably for two-and-a-half days. We may go outside the city. We will find out when we arrive"
Also on the trip were Mr Richardson's long-time aide on North Korea, K.A. "Tony" Namkung, Jared Cohen, director of Google Ideas - a think-tank run by the California-based Internet giant - and some staff, according to a statement from Mr Richardson's office.
The visit comes as Kenneth Bae, an American of Korean descent, is being held in North Korea after entering the country as a tourist in November.
KCNA says Mr Bae had admitted to committing a crime against the state.
Mr Richardson, who has visited North Korea several times over the past two decades, said last week he had been contacted by Mr Bae's son, who asked for his help.
North Korea has in the past agreed to hand over detainees to high-profile delegations led by the likes of former US president Bill Clinton, and some observers suggested it may have requested Schmidt's participation in this case.
But the US State Department has voiced concerns about the trip, saying it was ill-timed in the wake of Pyongyang's widely condemned rocket launch last month.
State Department spokeswoman Victoria Nuland said on Monday Washington's opinion had not changed, but hinted the two men might be asked to brief US officials about the trip afterwards.
"We are always open to hearing from Americans who've been in North Korea," she said.
North Korea last month angered the US and others by launching a long-range rocket. It said the purpose was to put a scientific satellite into orbit but Washington and other nations called it a disguised ballistic missile test.