Catt Sadler, who has worked for NBC-owned E! Entertainment for 12 years, explained the reasons for her decision on her website.
“It’s heartbreaking in one sense, but I believe that you have to act in alignment with your beliefs,” Ms Sadler said.
“As much as I wanted to stay, I do know my worth, I do know the inner workings of the network, and I just wanted what was fair and reasonable.”
In her post she added: “The way I see it, I have an obligation to be an agent for change.”
She has been praised by actresses Olivia Munn and Jessica Chastain on social media after finding out about the disparity in pay between her and co-host Jason Kennedy.
I couldn’t let another minute go by without acknowledging the overwhelming love and support I’ve been receiving the last 24 hours. Leaving E was one of the hardest decisions I’ve ever made, but your messages and heartfelt comments are comforting and affirm for me that I made the right decision. So many of you have similar stories, similar struggles, legitimate frustrations and I want you to know I hear you and feel for you. As a result, I have a renewed sense of purpose and genuine passion to right the wrongs. We are stronger together and I feel your strength at my core. If I had one ask, it is to please not place blame on my friend Jason Kennedy. He has done right by me in every respect. It hurts me deeply to see that some are vilifying him. I repeat, his hands are tied on this matter and if you’re angry – rightfully so – direct that emotion at the decision makers who failed us, not him. All my love + gratitude 🖤
A post shared by CATT SADLER // E! (@iamcattsadler) on Dec 20, 2017 at 8:17pm PST
Former host for E! Maria Menounos praised Ms Sadler’s decision, saying: “I know this wasn’t easy … good for you”.
In a subsequent Instagram post, Ms Sadler urged people not to “blame Jason”, saying “his hands are tied on this matter” and to direct any anger towards the channel and its owners.
In the time the post has been up, it has been liked more than 20,000 times.
NBC said in a statement that it would not discuss salaries, but that it “compensates employees fairly and appropriately based on their roles, regardless of gender”.
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Mr Kennedy is believed to have had more extensive duties than Ms Sadler at E! including work on the network’s red carpet on Live From the Red Carpet.
According to figures released by the National Partnership for Women and Families, in 2016 women in the US were paid on average 80 cents for every dollar paid to men, amounting to an annual gender wage gap of $10,470. (£7,826).