Following an allegation by Rooney, who told her 1.2 million Twitter followers she had spent five months attempting to work out who was sharing stories based on her personal social media posts and pointed the finger at Vardy's Instagram account, Vardy said she "never" speaks to journalists about her.
The reality TV star and wife of Leicester City striker Jamie Vardy wrote to Rooney: "If you thought this was happening you could have told me & I could have changed my passwords to see if it stopped.
"Over the years various people have had access to my insta & just this week I found I was following people I didn't know and have never followed myself."
The former I'm A Celebrity ... Get Me Out Of Here! star said: "I'm not being funny, but I don't need the money. What would I gain from selling stories on you?"
Vardy, who is pregnant with her fifth child, said she was "so upset" that Rooney had made the accusation, adding: "I'm disgusted that I'm even having to deny this.
"You should have called me the first time this happened."
Rooney claimed she had experienced a "burden" in her life in recent years as information from her personal Instagram page appeared to have been leaked from an account belonging to 37-year-old Vardy.
She wrote: "For a few years now someone who I trusted to follow me on my personal Instagram account has been consistently informing The SUN newspaper of my private posts and stories.
"There has been so much information given to them about me, my friends and my family - all without my permission or knowledge.
"After a long time of trying to figure out who it could be, for various reasons, I had a suspicion."
Rooney, 33, said she "came up with an idea" and that she blocked everyone apart from an Instagram page belonging to Vardy from seeing her Instagram stories.
She said: "Over the past five months I have posted a series of false stories to see if they made their way into the Sun newspaper.
"And, you know what, they did. The story about gender selection in Mexico, the story about returning to TV, and then the latest story about the basement flooding in my new house.
"It's been tough keeping it to myself and not making any comment at all, especially when the stories have been leaked. However, I had to. Now I know for certain which account/individual it's come from.
"I have saved and screen-shotted all the original stories, which clearly show just one person has viewed them.
"It's ... Rebekah Vardy's account."
The Sun has been contacted for comment.