The reality star will take to the diving board on 4 January when the Tom Daley-fronted series returns to ITV for a second run.
"I wanted to do it because so many people out there will be saying, 'Oh she is just a whale in the pool' - all the usual nonsense. But I'm a successful lady. I have just won a fashion award. By appearing on Splash!, I want to show that big girls are beautiful and that you can dive whether you're a size 8 or a size 20."
Gemma said that she's asked for plenty of sequins and crystals on her costume - "in true Essex fashion" - and is hoping as long as she looks the part, the skills will come too.
"I'm looking forward to wearing a sparkly outfit and proving to people that in life you can accomplish absolutely anything if you put your mind to it. Don't let your fears or your weight hold you back, just go for it. You don't have to look like a Victoria's Secret model to dive. Just shake your curves and rock your booty."
She added: "I'm doing this for normal women who might be self-conscious about things. I'm shaking my booty and doing it for the bigger girls."
Gemma is no stranger to pools, having spent plenty of sunshine-soaked holidays in party destinations like Ibiza and Marbella, although she admits Splash! is about as far away from that as she can get!
"When you're at the Ocean Club in Marbella it's all about getting out of the water looking a million dollars," she laughed. "You don't go there and start diving. That's not very fashionable. But I've thoroughly enjoyed the experience."
Splash!, hosted by Vernon Kay and Gabby Logan, returns Saturday, 4 January at 7.20pm on ITV.
Contestants taking part in the first heat alongside Gemma are Michael Strachan, Diversity's Perri Kiely, Hollyoaks' Gemma Merna and ex-EastEnders star Ricky Groves.