Jelena Mrdjenovich was born on June 24, 1982 in Hay River, Canada. She is trained and boxes out of the Partner Gym in Edmonton, Alberta. Aside from boxing, Jelena also plays basketball for University of Alberta. It was her father, a boxing fan himself, who suggested that her daughter should try boxing. She accepted the challenge and became a pro initially. Now she is trained by Milan Lubovac.
Jelena fought in 15 amateur bouts including exhibitions. In 2002, Selena lost to Debbie Richards of London for the Canadian National Championships in St. Catharines, Ontario for the silver medal.
At Shaw Conference Centre in Edmonton, Alberta, on January 24, 2003, Jelena won her professional debut match over Cathy Boyes of Kamloops, British Columbia by a Technical Knockout in the fourth round. After eight months, Jelena again won a match against Robin Bealieu of Fort Smith, Northwest Territories with ease in the first round by a knockout. In December of same year, she improved her professional record to 3-0 (2 KO) over Olga Heron of Mississauga, Ontario.
In January 2004, unranked Shannon Gunville of Bismarck, North Dakota was defeated by Mrdjenovich at Fort Garry Place in Winnipeg, Manitoba, Canada with a Technical Knockout. In May 2004, Ragan Pudwill of Mandan, North Dakota was defeated as well by a knockout. Jelena seemed to have no trouble working on her punches against her smaller opponent. Mrdjenovich continued to win two more bouts that year. One was with Olga Heron of Mississauga, Ontario with a clear six-round unanimous decision at Shaw Conference Centre in Edmonton and one with Olivia Gerula Pereira at the Convention Centre in Winnipeg, Manitoba.
In March 2005, Jelena and Tracy Carlton of Compton California did a rematch at Ranchman’s Bar in Calgary. Carlton fell to 0-8-1 allowing the 6th rounder to win by a Technical Knockout.