AT&T's admission came after a lawyer for porn star Stormy Daniels claimed the company, drug giant Novartis and a company controlled by a Russian oligarch had all made payments to Cohen's shell company.
Daniels' lawyer, Michael Avenatti, said AT&T had made four separate payments of $50,000 apiece to Cohen's company, for a total of $200,000 in late 2017 and into early 2018.
That company, Essential Consultants, was created by Cohen in October 2016 and soon after was used to make a $130,000 hush-money payment to Daniels.
In a prepared statement to CNBC, AT&T said Cohen's company "was one of several firms we engaged in early 2017 to provide insights into understanding the new administration."
"They did no legal or lobbying work for us, and the contract ended in December 2017," AT&T said.
The company did not say how much it had paid Cohen, who was the president's personal lawyer at the time.
In a report on Cohen's company, Avenatti's law firm said that Novartis in late 2017 and early 2018 made four separate payments to Essential Consultants totaling nearly $400,000.
"Following these payments, reports surfaced that Mr. Trump took a dinner with the incoming CEO of Novartis before Mr. Trump's speech at the World Economic Forum in Davos, Switzerland in late January 2018," Avenatti's report said.
That CEO, Vas Narasimhan, was joined with a group of other companies' executives at that dinner.
A Novartis spokesperson said in a statement that "any agreements with Essential Consultants were entered before our current CEO taking office in February of this year and have expired."
The White House declined to comment on whether Trump knew about payments to Cohen from AT&T, Novartis or Columbus Nova, the company linked to the Russian oligarch, and instead referred questions to the president's outside legal team.
Avenatti's report says another company, Korea Aerospace Industries LTD, paid Essential Consultants $150,000 in November 2017.
Avenatti's client Daniels, whose real name is Stephanie Clifford, was paid $130,000 by Essential Consultants on the eve of the 2016 presidential election.
Daniels says the money was in exchange for her signing a deal that required her to remain silent about an affair she claims to have had with Trump in 2006, shortly after the birth of his youngest son.
The White House has denied that Trump had sex with the adult film actress.
Cohen did not have an immediate comment on Avenatti's new allegations about payments to Cohen's company.
CNBC's Eamon Javers contributed to this report.