Unannounced media statement follows report he was on verge of quitting over the summer.
Tillerson's statement followed a report by NBC News citing unnamed senior administration officials as saying he was on the verge of resigning over the summer amid mounting policy disputes with President Donald Trump and that Vice President Mike Pence urged him to remain secretary of state at least until the end of the year.
"The vice president has never had to persuade me to remain as secretary of state because I have never considered leaving this post," Tillerson said at the news conference.
"What we have accomplished, we have accomplished as a team," he said, reaffirming his "commitment to this role".
Citing the three anonymous officials, the NBC report also claimed Tillerson called Trump a "moron" after a July 20 meeting at the Pentagon with members of Trump’s national security team and Cabinet officials.
"The places I come from, we don't deal with that kind of petty nonsense." the former Exxon Mobil CEO said. "I'm just not going to be part of this effort to divide this administration."
Trump "loves this country. He puts Americans and America first. He is smart," he added. "He demands results wherever he goes and he holds those around him accountable."
In a post on Twitter moments before Tillerson spoke, Trump said: “NBC news is #FakeNews and more dishonest than even CNN. They are a disgrace to good reporting. No wonder their news ratings are way down!”