She was suspended from Celebs Go Dating for creating and running multiple secret trolling accounts used to target her former co-host. She later resigned from the show.
At one point Mr Blackman was targeted 42 times in one day. He has described her signing the undertaking as “a moment of vindication”.
Ms Essex must remove a number of social media posts and online articles and the agreement prevents her from harassing Mr Blackman on social media or in print.
She could face fines, have her assets seized, or be imprisoned if comments are found to contain content deemed as harassment.
“This is a crucial moment for me after years of suffering in silence with unfounded allegations,” said Mr Blackman.
“I was forced to take this action and it is a vindication of the false claims Ms Essex made against me.”
The presenter said he had concerns about the behaviour of his former co-star during the filming of series three and four of the hit TV show when tweets appeared about him.
“I became aware of several Twitter trolling accounts that were relentlessly targeting myself and other innocent people,” said Mr Blackman.
“I discovered all were registered with a mobile phone number ending in 05. This matched Nadia’s mobile phone number.”
Mr Blackman requested she stop harassing him and asked for her to apologise to him.
Ms Essex then raised an employment tribunal against him, accusing him of bullying and harassment, but it was thrown out 10 months later.
It was ruled her claims were brought forward outside the three-month legal time limit. She has admitted running the accounts, but blamed her mental state at the time.
Ms Essex said after the case: “I chose the wrong path. But, I’m human. And now I know better, and now I understand and I know I could never go there again.”
Mr Blackman said that even after the case was thrown out in July 2019 the attacks continued. “It escalated further,” he said. “Two days after the judge had rejected her claim, Nadia uploaded a 12-minute YouTube video solely about me.
“She made more untrue allegations and promoted it across her own social media accounts.”
Eventually the messages got too much, he added. But Mr Blackman claimed he postponed legal action after his former co-host announced her pregnancy. “I spoke to my lawyer.
I was informed Nadia’s behaviour ‘sailed past harassment’. We decided to issue legal harassment proceedings once I was back from a holiday in mid-September 2019.
“After I came back, Nadia announced she was pregnant. Despite being told I didn’t have to, I decided to delay my proceedings until after the birth, six months later.
“When I issued my legal process, Nadia’s immediate response was to agree to sign legal undertakings to never harass me again in the press, social media, online, in person, in conversation etcetera.”
Mr Blackman warned that other stars facing similar attacks need protection. “This experience has had a debilitating effect on my trust in people and mental health.
“I can now wake up every morning without fear of what she is going to allege on social media.
“Her obsession with me was not welcomed or invited. I’m so relieved Nadia has agreed to stop harassing me.
“Her actions were indefensible and her compulsion with trying to ruin my reputation caused a great amount of pain. I hope this is the end of this matter. We have to be more mindful about how we use social media.”
Ms Essex didn’t respond to requests for comment.