The Israeli actress looks sensational in the new flick, which is thrilling fans at cinemas this weekend.
But wearing the outfit left her in agony – and she says filming in Britain wasn’t much fun.
In an exclusive interview, Gal, 32, said: “The first time you put on the costume is a big moment for anybody playing the role of a superhero – and it was no different for me.
“I remember putting it on and it being so tight I couldn’t breathe. But I was so grateful to be playing Wonder Woman that I didn’t say anything.
“Also, we were filming in London during the winter and here I am in this tiny costume and it’s freezing. And then it starts raining.
“During breaks I would be stood there with my cape over the heater. I didn’t care, though. It was just an honour to be playing Wonder Woman.”
Gal stuck to a strict diet for months to prepare for the role, while a tough training regime saw her put on 17lbs of muscle.
But her time in the armed forces made that a doddle.
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Gal said: “You have to get in shape for any superhero movie but for me that wasn’t a massive deal.
“Believe it or not, I was a combat instructor in the Israeli Army and I have always kept myself in good shape.
“But I did have to get a bit stronger for the movie and now I look in the mirror and think, ‘where did these guns come from?’ But I like it.”
In the past Gal has been a beauty queen and model for fashion giants including Gucci and Miss Sixty.
She had her big acting break in The Fast & The Furious franchise alongside Vin Diesel.
Last year Gal made her debut as Wonder Woman – aka Diana Prince – in Batman v Superman: Dawn of Justice.
Her latest outing sees her character head to Britain to try to end the horror of the First World War.
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Gal said: “Traditionally, lead roles in superhero movies are male but I didn’t think so much about it being a female-driven movie.
“Diana has it right – she comes from a world where men and women are the same. There is no difference. I wanted to focus on her qualities. She is compassionate, brave, kind, loves people. In the world we live in today it’s those qualities she has that I wanted to be the inspiration, not her gender.”
Gal has been praised by critics for her performance as Wonder Woman, with one describing her as an “inspired choice”.
Another review said she had “star power” and said she was “awesomely fierce and surprisingly funny”.
Brits have been flocking to see the movie at cinemas since it was released here on Thursday.
The film, which also stars Chris Pine, is tipped to be one of the biggest box office hits of the summer.