Alicia Kemp, 25, struck Thanh Phan, 51, while riding through Perth about 8.40pm on May 31.
Mr Phan was critically injured and died in hospital several days later.
Kemp was charged with dangerous driving occasioning death under the influence of alcohol, and dangerous driving occasioning bodily harm under the influence of alcohol.
She appeared in Western Australia's Magistrates Court on Monday via video-link and pleaded guilty to dangerous driving occasioning death under the influence of alcohol.
Prosecutors dropped the bodily harm charge.
Outside court, defence lawyer Mike Tudori said his client had acted stupidly and now wanted the court process to be completed as quickly as possible.
"She is nervous and worried, she's a young foreign national girl in our prison (system)," he told reporters.
"She's relieved that one of the charges has been discontinued, and now she'll just move towards preparing for a sentencing later on in the year for this tragic death."
Mr Tudori said he'd like the sentencing process completed by Christmas.
"She's obviously done something stupid at the time," he said.
"She obviously wasn't thinking, level-headed and there's consequences, and she just wants to get on with her life."
Mr Tudori said Kemp's family in the UK were concerned and worried for her and that she was being supported in WA by her boyfriend.
Mr Phan's family has described him as a "beloved husband, father of two, brother, and dear friend".
Kemp suffered minor injuries in the collision.
Her 26-year-old female pillion passenger was also taken to hospital for treatment of non-life-threatening injuries.
Kemp, who was previously refused bail, was remanded in custody to appear in the District Court on October 31 for a sentencing mention.
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