Separately, in an exchange with Senator Bernie Sanders, Pruitt said "Senator, I believe that the [EPA] administrator has a very important role to perform in regulating CO2".
Those comments come as President Donald Trump weighs whether to pull the United States from the Paris agreement on climate change, a landmark 2015 deal in which the leaders of close to 200 countries agreed to reduce greenhouse gas emissions in the decades to come.
Pruitt's statements fly in the face of the global scientific consensus on climate change - which has concluded that it is "extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century".
During his confirmation hearing in January, Mr Pruitt did, however, say he believed humans had contributed to climate change, but he was not sure how much.
Today's remarks by EPA administrator Scott Pruitt that human activity is not "a primary contributor to the global warming that we see" should effectively bring an end to the term formerly known as "climate denial".
Pruitt's statement runs contradictory to his own agency's research.
"We can't afford to reject this clear and compelling scientific evidence when we make public policy".
"Carbon dioxide (CO2) is the primary greenhouse gas pollutant, accounting for almost three-quarters of global greenhouse gas emissions and 84% of USA greenhouse gas emissions", according to the website.
Pruitt said the Supreme Court's decision should not have been viewed as permission for the EPA to regulate carbon dioxide emissions.
Pruitt has previously said the EPA should not regulate Carbon dioxide without a law passed by Congress authorizing it to do so.
"The finding is the backbone of the Obama administration's climate regulations, since it obligates the EPA to regulate emissions if it finds it necessary to do so".
Pruitt declined to respond to a question from a reporter after his Houston speech on whether he would now seek to overturn the endangerment finding.
Pruitt took umbrage with the Obama administration's concerted efforts to put an end to climate change, joining with other Republican attorneys general to take legal action against President Obama 14 times throughout his tenure.
The White House and Pruitt have proposed a budget for the EPA that would cut the agency's budget by $2 billion and eliminate 20 percent of the workforce, including the entire Office of Environmental Justice.
"The mask is off". Scientists are attributing it to climate change - something that likewise shouldn't surprise anyone who isn't trying to capitalize on global destruction or deny that it's happening for political reasons. Almost 200 countries from around the world have agreed to try to limit temperatures from rising more than 2°C (3.6°F) under the Paris Agreement, but research has shown that the world remains far from hitting such a target.