The US superstar, whose real name Stefani Germanotta, made her red carpet debut with entrepreneur and investor Polansky on Wednesday at the world premiere of her new film Joker: Folie A Deux at the Venice International Film Festival.
In an interview with US Vogue, she revealed that her mother set them up after meeting Polansky through philanthropic endeavours.
Discussing their relationship, Germanotta told the magazine: "I had never met anyone like Michael. He's so smart and so kind. And his life and my life are very different.
"He's a very private guy and he's not with me for any other reason than that we are right for each other.
"But I think what I want my fans to know is that I'm just, like, so happy. I'm healthy.
"I feel like the last time they heard from me - in this way - was Chromatica, (her sixth album released in 2020) and that album was about an absolutely horrible time for me with my mental health.
"I was in a really dark place. I struggled for, like, many years before that.
"But everything started to change. Because I had a real friend who saw the ways in which I was unhappy and why. And he wasn't afraid to truly hold my hand. And get to know me. On a very deep level."
The singer-songwriter, who has been engaged twice before to actor Taylor Kinney and to talent agent Christian Carino, said she feels the missing piece in her life was "having real love".
The couple met in 2019 after Gaga's mother, Cynthia Germanotta, who co-runs the non-profit Born This Way Foundation which supports young people's mental health, met Polansky in philanthropic circles.
"My mom met him and she said to me, 'I think I just met your husband', and I said, 'I'm not ready to meet my husband!'", she recalled.
"I could never have imagined that my mom... found the most perfect person for me."
She said she "fell in love" after their first date and then the COVID pandemic hit, leading them to move in together.
Reflecting on that period, she said: "It was really kind of special. I'd been so focused on my career since I was a teenager.
"And the gift of that time was that I got to completely focus on my relationship. I met this totally supportive, loving human being who wanted to get to know me - outside of Lady Gaga."