In response, Ms Murray wrote: "Today Jeremy Corbyn went to his local mosque for Visit My Mosque Day, and was attacked by a Brexiteer.
"Rachel Riley tweets that Corbyn deserves to be violently attacked because he is a Nazi. This woman is as dangerous as she is stupid. Nobody should engage with her. Ever."
Ms Riley launched legal action.
In a judgment published on Friday, Mr Justice Nicklin said: "An imputation that a person had publicly supported a violent attack on someone is plainly defamatory at common law.
"It is conduct which would substantially affect, in an adverse manner, the attitude of other people towards the claimant or have a tendency so to do."
But Mr Justice Nicklin rejected Ms Murray's lawyer's claim that she was expressing an opinion when she asserted Ms Riley had said Mr Corbyn "deserved to be violently attacked".
He said this was "a simple factual statement and would be understood as such".
