The prestigious magazine offered no details on the allegations against Lizza, 43, the latest media figure to face consequences amid a wave of harassment allegations surfacing in recent weeks.
"The New Yorker recently learned that Ryan Lizza engaged in what we believe was improper sexual conduct," the magazine said in a statement.
Time names sexual abuse 'Silence Breakers' as Person of the Year
"We have reviewed the matter and, as a result, have severed ties with Lizza. Due to a request for privacy, we are not commenting further."
In a statement to US media, Lizza said the firing was made "hastily and without a full investigation of the relevant facts," which he said involved a woman he was dating.
"I am dismayed that The New Yorker has decided to characterise a respectful relationship with a woman I dated as somehow inappropriate," Lizza was quoted as saying.
"The New Yorker was unable to cite any company policy that was violated."
The law firm representing Lizza's accuser -- who wishes to remain anonymous -- issued a statement of its own, pushing back at his version of events and saying that "in no way did Mr Lizza's misconduct constitute a 'respectful relationship' as he has now tried to characterise it."
"Our client reported Mr Lizza's actions to ensure that he would be held accountable and in the hope that by coming forward she would help other potential victims," the statement added.
CNN, where Lizza has been a contributor, said the writer would not appear on the news channel "while we look into this matter."
Uma Thurman breaks silence on Harvey Weinstein with chilling message
Earlier this year, Lizza's report from an interview with Scaramucci ended the brief White House career of the longtime Wall Street banker. The article stemmed from an expletive-laden interview with the former hedge fund manager who lasted just 10 days in the White House.
COMMENTS
Comments are moderated and generally will be posted if they are on-topic and not abusive.
For more information, please see our Comments FAQ