Lady Gaga and fiance Michael Polansky make red carpet debut in Venice

Lady Gaga turned heads with a dramatic look at the Venice International Film Festival, stepping out on the red carpet with fiance Michael Polansky for the first time.

The US star, 38, appeared at the Italian festival for the world premiere of Joker: Folie A Deux alongside co-star Joaquin Phoenix.

She arrived on the red carpet in a Christian Dior black dress with a plunging neckline and scalloped skirt, paired with a theatrical lace headpiece from Philip Treacy and sparkling jewellery from Tiffany & Co.

It marked the first major red carpet appearance with her fiance Mr Polansky – an entrepreneur and investor.

She confirmed her engagement as she watched the swimming finals at the Paris Olympics, introducing Mr Polansky as “my fiance” to the French Prime Minister Gabriel Attal.

Gaga plays Harley Quinn, love interest of the Joker (Phoenix), in the new film from Todd Phillips – which comes five years after the first film won the coveted Golden Lion.

She said she made the decision to star in films including Joker: Folie A Deux to “help people feel good about life” and allow them to “escape into another world”.

Speaking at an earlier conference about why she chose to move into acting, Gaga said: “The reason I started making music when I was really little was because I just had something to say, and trying to figure out how to do that.

“One of the reasons I love music and I love movies so much is the stories that you get to tell, and the way that we get to express something to the world that will hopefully help people feel good about life and give them a moment to escape into another world to fall into somebody else’s story.

“I think that what I really meant to say is that I believe that movies have a tremendous power to change the way people feel, and that’s part of why I love to create.”

Gaga went on to say that working with Phoenix had been “a total breeze” and said she had decided to work on the film because of its “interesting story”.

She added: “I think we all really thrived in the moment and in the chaos of it all, this is such an interesting story.

“The way that Todd tells this story, I think if you’re imagining what this movie is like, and then you go see it, you’ll realise that you couldn’t have possibly thought of it on your own.

“And in order to make that happen we had to find it everyday, what was the truth, what was the honest moment in each scene, and how did it tell a story.

“Quite frankly, I think we really want all of you to decide for yourselves when you see the film, what it means to you.”

The Bad Romance singer was joined at the festival by co-star Phoenix, who revealed he had a dream about performing as the Joker, which led to him calling Phillips.

He said: “The dream is not what inspired the movie, the dream was just, I had this dream that I was performing as the Joker doing songs, and I just called Todd and said there might be something there.”

Phoenix, 49, was also asked why he dropped out of Todd Haynes’ gay romance film, but declined to comment on why.

He said: “I think if I do, I would just be sharing my opinion, from my perspective, and the other creatives aren’t here to say their piece, and it just doesn’t feel like that would be right.

“I’m not sure how that would be helpful, so I just don’t think I will.”

Joker: Folie A Deux will be released in UK cinemas on October 4.

It follows the story of the Joker and Harley Quinn meeting while incarcerated at Arkham State Hospital, and after he is released the pair embark on a doomed romantic adventure.