In an email sent to staff, Seven West Media CEO James Warburton thanked Mr Roberts-Smith for his work at the company.
"Ben has been on leave whilst the case was running and today has offered his resignation which we have accepted," Mr Warburton said on Friday.
"We thank Ben for his commitment to Seven and wish him all the best."
The 44-year-old's claim of defamation was dismissed on Thursday after a Federal Court judge found a number of articles published in 2018 in The Sydney Morning Herald, The Age and Canberra Times implicating the retired SAS corporal in war crimes between 2009 and 2012 were substantially true.
Attention has turned to the Victoria Cross recipient's legacy, with calls by Greens Senator David Shoebridge for Mr Roberts-Smith's uniform to be removed from the Australian War Memorial display.
Former special forces soldier Heston Russell pointed out that the court's findings in the civil case did not relate to the incidents that led to Mr Roberts-Smith's Victoria Cross or Medal for Gallantry.
"There's a bit of pile-on at the moment and we need to afford Ben and his team due process because this was a civil proceeding," he told Nine on Friday.
Former soldier, Neil James, said the case as to whether Mr Roberts-Smith was criminally liable remained entirely separate and "hypothetical".
Mr Roberts-Smith has not been officially charged with any crime and maintains his innocence.
"Just because you lose a defamation case, doesn't mean that you're going to be charged with war crimes," the executive director of independent watchdog the Australia Defence Association said.
"They're unconnected."
Mr Roberts-Smith may still face criminal charges by the Australian Federal Police and Special Prosecutor but any outcome would likely take years, Mr James said.
He called for action on the war crimes outlined in a groundbreaking report by the Inspector-General of the Australian Defence Force in 2020.
Major General Brereton's inquiry found credible information of 23 incidents in which 39 individuals were unlawfully killed by Australian soldiers in Afghanistan.
"The fact that no Australian has yet been convicted of that (committing war crimes) doesn't alter the fact that they happened," Mr James said.
"Therefore, the ADF and the country have to do certain steps to stop them happening again."
