The 45-year-old News Correspondent worked at ITV for 21 years on breakfast shows GMTV, Daybreak and most recently GMB, but has made the decision to switch to rival channel GB News to co-host The Live Desk.
Tomson revealed: "When the opportunity arose to join GB News, I was in a bit of a pickle. It sounded enticing and exciting but I’d spent the bulk of my 21-year television career at ITV.
"The hours were bonkers but I worked with a great team who helped make the job full of fun, even at 3am when my eyes were droopier than a Bloodhound’s.
"I was also well aware of the flak directed at GB News. Much of it from those types who profess that they’re tolerant members of the ‘Be Kind’ brigade (yawn) but are actually some of the most intolerant people you could ever hope to meet if you don’t profess to share their views. Which always makes me laugh."
Thomson added that GB News offered her a chance to be herself, saying: "Those who know me would probably describe me as straight-talking, authentic, feisty and fearless. Not all broadcasters would encourage that but GB News is different and I’m loving that freedom and individuality."
The journalist and presenter confessed she had personally struggled with the decision to leave ITV, until she spoke to a "famous broadcaster" she chose not to name, who persuaded her it would be an adventure.
She said: "I sought out the advice of some of the less tribal folk including one of the most famous broadcasters in the business. I don’t want to name them but they’ve always been incredibly generous in terms of advice, feedback, reflections on the industry and how to deal with those delightful social media trolls.
"'It’s a no brainer,' came the answer. 'You’ve got to do it. It’s very exciting for you and a proper adventure.'"
Tomson added that she hopes to, "challenge and hold to account the powerful types and offer a voice to those who want to be heard but are thoroughly disillusioned so don’t bother to engage.
"I want to help change that and redress the balance, without fear or favour."
Other presenters the GB News roast include Nigel Farage, Laurence Fox and Sir Jacob Rees-Mogg.
He was said to be in talks with GB News, but now has his own show on TalkTV.