Betsey Johnson is known for her circus-like fashion shows — complete with riotously patterned clothes and the designer herself cartwheeling on the runway.

Turns out, her personal life has been even wilder.

In her new “Betsey: A Memoir,” she dishes on everything from terrible romances to a mysterious abduction in Eastern Europe.

It all began innocently enough.

“My upbringing was very positive and clean and pure.” said Johnson, 77. She grew up in small-town Connecticut and dreamed of becoming a Rockette. While a senior at Syracuse University, she won a spot in Mademoiselle’s guest-editor competition.

Johnson made her own short-sleeved sweaters, which ended up in the magazine — and accidentally launched her fashion career.

“One of the first orders . . . was from [“Vertigo” actress] Kim ­Novak,” she writes. Soon, she was designing for NYC brand Paraphernalia, creating clothes worn by Julie Christie and Twiggy.

At night she was hanging out with Andy Warhol’s crowd at Max’s Kansas City and dating Sterling Morrison, guitarist for the Velvet Underground. But then she started falling for Morrison’s bandmate, John Cale.

“I fell in love immediately,” she said. The new couple quickly wed at City Hall. Warhol and Cale’s bandmates (including Morrison) were there, yet it never occurred to Johnson to invite her family.

Cale, she writes, was “practically living the lyrics to Lou’s song, ‘Heroin.’ ” It got so bad that, a year in, the two stopped having sex and he was kicked out of the band. The couple split, Cale got clean, and they remain friendly: “He was my favorite husband,” Johnson said.

It wasn’t much of a competition. “I was so out to lunch with men and relationships,” she said.

There was “Joe,” whom she describes as “icy.” After their daughter, Lulu, was born, Johnson moved out. One night, she found Joe trying to scale the exterior of her new home. She got a restraining order.

“Later, I got a call from a woman who said she was Joe’s wife. She wanted me to support Joe, her and their four children,” she said.

Then there was the “burger flipper” at the Cupping Room in Soho. That union was over before the honeymoon ended: As they landed in Puerto Rico, she discovered he was an addict and ended it right away. (She writes that he later died of an overdose.)

All the while, Johnson’s career continued its ascent. On her way back from a work trip to India, the plane made an unexpected detour to Dubrovnik. Yugoslavian officials asked to see ­everyone’s passport. A frightened Johnson was thrown in a van by two men, who were flanked by cops with guns drawn. They drove to a building and shut her in a room.

When a woman entered, asking questions in a foreign language and coming at her with a needle, Johnson went berserk.

“I started screaming and shouting and flailing my arms,” she writes. The woman left, and Johnson escaped when another worker brought her outside for some air — only to be caught by police and returned. Finally, an English-speaking doctor explained there had been a cholera outbreak in India and, due to a clerical error, it looked as if she hadn’t had all her shots. “I had ­indeed been inoculated!” she said.

In 1971 she won the prestigious Coty Award and heard through the grapevine that fellow fashionistas Donna Karan and Diane von Furstenberg were “riled” because they didn’t think of her as a true designer.

“I was shocked myself because I never connected with the traditional fashion world,” Johnson said.

She launched her namesake brand in 1978, and her empire grew to 66 stores nationwide. The designer’s life continued to be a roller coaster, including a breast-cancer diagnosis in 2000. She’s now in remission.

She sold her brand in 2007 and, after the new owners filed for bankruptcy, fellow designer Steve Madden saved it. Johnson — now based in Malibu — is the creative director.

And despite her freak-show love life, she hasn’t given up on romance.

“I am dying to meet a guy!” she said. “I had a great lover for about four years. But all of a sudden, he disappeared about three months ago. It was the best sex I’ve ever had.”