Kohle was born in Beausejour, Manitoba, Canada. According to Kohle’s main agency Panache Management, she began her modeling career in 2000, while according to her sister Bridget Kohle, she began her career in 2002 after winning a local model search contest.  She was represented by agencies in Toronto, Canada, New York, USA, Athens, Greece, Istanbul, Turkey, Milan, Italy, Hamburg, Germany, and London, UK. Based in these cities, she had modeled internationally for seven years by 2008.  On October 11, 2008, Kohle was found dead in Italy. She died after falling from the seventh-floor balcony of an apartment at Milan, and Italian police ruled it a suicide by jumping. She had been there for just over a year after signing a contract with a modeling agency through the Panache modelling agency in Winnipeg. She was 26.

Ugo Besozzi, head of Future Models, the Milan-based agency Kohle joined in January 2008, was quoted as saying “The girls there told the story. Everyone said the same thing: At one point she said that she was going to smoke a cigarette. She opened the window and drastically took that decision. There was no warning and nobody could have done anything about it”.  Kohle’s sister Bridget checked Hayley’s e-mail account and could see the last message Hayley sent was one to her, just days before the death, which said she was very excited about good news she’d received about a big modelling job.  A memorial for Kohle was held on October 20 at St. Mary’s Catholic Church in Beausejour.