Opening up in a recent interview, the 23-year-old confessed she first realised she was attracted to both guys and girls four years ago, back when she was 19 years old.
She chose, however, not to publicise it as she was 'constantly worrying' about it, but has now decided to come out as bisexual in the hope that it will encourage others in a similar situation to her to do the same.
Speaking to Heat magazine, Marnie explained: "When I was 19 I realised I would look at some girls in a different way. I've always kissed girls, but I don't think I took it seriously until I had an encounter with a girl last year. To me, that was different because it was just me and her. It wasn't for any other reason than I wanted to, so it made me think differently."
Since revealing she is bisexual, Marnie has said she "already feels better" and thinks it is "empowering." The reality star added: "Me being honest about my sexuality might make others want to be as well."
Marnie didn't rule out having a relationship with a girl either. She admitted it could be a possibility for her in the future.
Her comments came after Marnie recently tweeted about her sexuality. She told her 748,000 followers: "I'm sure I'm bisexual. Not even kidding. I kiss just as many girls as boys these days."
Although her tweet now appears to have been deleted, Marnie has liked several posted by fans that have complimented her on speaking publicly about her sexuality.
One tweet read: "So inspiring that @MarnieGShore has came out as a bisexual." While another gushed: "@MarnieGShore so so much respect for you! So proud of you and I'm so glad you are happy."
She is currently romantically linked to her co-star Aaron Chalmers.
Fans of Geordie Shore have recently seen Marnie return to their screens. She was a late arrival to the current series, after she chose to return to the show following her failed engagement to ex-fiancé and former TOWIE star Ricky Rayment.
Her co-stars were surprised to see her and Marnie's on/off flame Aaron admitted he was "buzzing" to have her back again. Viewers have since seen Marnie and Aaron pick up their romance and the pair recently confessed they love each other!
We're not kidding. Both Marnie and Aaron dropped the L-bomb to each other. Ok, Aaron's took a little pushing from Marnie, but she was still pretty chuffed to hear that the feeling is mutual between herself and the tattooed charmer.
Marnie has since said she is hoping herself and Aaron can make their relationship official one day. Sharing her hopes for the pair, she recently told the Mail Online: "It was different [being on the show as a single girl]. I went in there to see what was happening with me and Aaron. Although I was newly-single, I wasn't interested in going out on the pull... I only had eyes for Aaron."
"I'd like to think we could [be official one day]," she revealed. "We both need to stop playing games and take the plunge."
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