The appeals of two female assistants against similar periods of detention were also thrown out.
The Nobel peace laureate was sentenced last August to an additional 18 months under house arrest after being convicted of breaking the terms of her detention by sheltering an uninvited American man who swam to her lakeside villa.
She had initially been sentenced to three years in prison with hard labour, but that sentence was immediately commuted to 18 months of house arrest by Senior General Than Shwe, the head of Myanmar's ruling military.
Her lawyers appealed against the sentence to the supreme court in November last year after a lower court upheld the decision to extend her house arrest.
Aung San Suu Kyi has already spent most of the past 20 years in jail or under house arrest.
Speaking to the Associated Press on Thursday, her lawyer Nyan Win, said he was confident the court ruling would go their way.
"This is an indication that the govt is not ready to release her, which means she will not be participating in the upcoming election. It also means the election will not be inclusive, free or fair"
Aung Zaw, Irrawady magazine editor
"We strongly believe that Daw Aung San Suu Kyi will be acquitted. We have presented strong legal points during our final argument last month," he said.
"Daw" is a term of respect for older women used in Myanmar.
Aung Zaw, editor of the Thailand-based magazine Irrawady, told Al Jazeera that he was not surprised with the outcome.
"This is an indication that the govt is not ready to release her, which means she will not be participating in the upcoming election," he said. "It also means the election will not be inclusive, free or fair."
He said heavy sentences have also been handed down on political activists during the UN human rights investigative visit a few weeks ago.
"There has been a clampdown on political activists in the country, so I don’t see any kind of optimism… any hope at all prior to the election.
"This is going to be a military-sponsored election and this government is going to legitimise its own rule," Aung Zaw added.
Friday's court ruling comes nearly two weeks after the release of Tin Oo, the 82-year-old deputy leader of Aung San Suu Kyi's National League for Democracy party, after nearly seven years in detention.
It also comes a week after a UN human rights envoy left Myanmar, expressing disappointment that he had not been allowed to meet the opposition leader.
|Aung San Suu Kyi's deputy Tin Oo was
released earlier this month [AFP]
Speaking after his release Tin Oo said he was very hopeful that Aung San Suu Kyi would be released soon, noting that in 1995 he was released from an earlier stint in prison not long before Aung San Suu Kyi herself was freed.
Last month a report quoted a senior Myanmar official as saying the government was planning to free Aung San Suu Kyi in November, when her current term of house arrest comes to an end.
The report cited sources who attended a meeting with Myanmar's home minister, Major General Maung Oo, who also said that Tin Oo would be released in February.
A November release for Aung San Suu Kyi would come a month after many observers believe Myanmar will hold its first parliamentary elections in two decades.
The government has said the vote is a key part of what it says is a "roadmap to democracy, but critics say the plan will only reinforce military rule.
No firm date has yet been set for the election.