Her heartbroken father, who she lived with in the French Alps, paid tribute to the young star.
Tony Soutter said: "This cruel world took my Soul mate and 'Bessie' from me yesterday on her 18th birthday.
"I was so proud of the beautiful young woman she had turned into. Ellie I will miss you more than you could have ever imagined. Rest in peace you little Champion!"
Ellie had been preparing to compete for the British team in the Junior World Championships in New Zealand, in August.
At the time of her death Ellie, a youth Olympian, was coached by French Olympic snowboarding sensation Deborah Anthonioz.
Ms Anthonioz won a silver medal in women's snowboard cross at the 2010 Winter Olympics before retiring from competitive snowboarding in 2014.
Dedicated to her sport Ellie spent winters on the Junior Freeride Tour and the SBX Europa Cup circuit and travelled to New Zealand in the summer - to continue training.
Team GB said: "The British Olympic Association is saddened to hear of the sudden passing of snowboard cross athlete Ellie Soutter, aged 18.
"Our thoughts are with her family and friends at this sad time."
Miss Soutter who grew up in Surrey before moving to the Alps was looking for full commercial sponsorship to keep her on track to compete in the Olympics, earlier this year.
In February, her father said on Facebook she was in need of funding during Freeride Junior Tour. One season in the sport came to a staggering £24,000 - and there was no available funding from Team GB, he said. Mr Soutter was attempting to raise much of the cash for her via supporters and crowdfunding, while searching for full time backers.
This meant she was having to break from the circuit in February 'due to lack of funds'.
In April, fund management firm Carne announced they were sponsoring the teen - who was getting set to compete again next month after a call up for Team GB for August's Junior Snowboard World Championships in New Zealand.
Miss Soutter, also an ambassador for Les Gets Ski Station in the French Alps, lived in Les Gets in the French Alps where she first learnt to snowboard at the age of ten.
BOA Chair Hugh Robertson and BOA Athlete Commission Chair Ben Hawes said: 'Ellie was an incredibly popular and well-liked member of the team.
'Our thoughts are with her family and friends at this sad time'.
Athletic Miss Soutter was also a lover of the outdoors - often sharing images of herself biking, hiking and climbing.
Ellie was a star in two specialisms.
Freeriding is takes place 'off piste' on big mountains allowing riders to show off their skills.
While boardercross saw Ellie 'competing against 3 other girls down a course with different features such as berms and jumps'.
After her win in Turkey, aged just 16, Ellie told British Ski and Snowboard (BSS): 'I don't think it's quite sunk in yet. I'm a little bit emotional. I cried as I crossed the line.'
British Ski and Snowboard said 'Ellie was one of the country's best up-and-coming snowboarders, competing in both snowboard cross and freeride.
'She was an inaugural member of the British Europa Cup snowboard cross programme which commenced earlier this year.
'The thoughts and condolences of the British ski and snowboard community are with Ellie's family, friends and teammates.'
