Both her defence team and the prosecution have said they will appeal the sentence, the latter party saying 20 years is too lenient.
A bench of three judges in Bali found the former beauty student guilty of carrying 4.1 kilograms of marijuana into Denpasar last October.
Corby, 27, has emphatically denied the charges, claiming the marijuana was planted in her body board case, and that she is the victim of a drug smuggling racket.
The Australian government has offered Corby’s defence team the help of two QCs with Indonesian legal experience, pro bono, to help with her appeal.
The offer has been made before but turned down.
The government said it has provided tens of thousands of dollars in assistance to Corby’s defence.
“And obviously we will consider any application from Schapelle Corby’s defence team for further financial support to assist with the appeals,” said Foreign Minister Alexander Downer.
Angry talkback radio callers and posters on website forums have called for a travel boycott to Bali to protest the verdict.
Australian Prime Minister John Howard said he feels for Corby.
“I say at the outset, that guilty or innocent, I feel for this young woman,” Mr Howard said.
“If she is guilty I feel for her, that a tragic mistake and tragic act has done so much damage to her young life. If she is innocent, my feelings for her are redoubled.”
The Australian government will now focus on negotiating a prisoner transfer agreement with Indonesia, which would allow Corby to serve her sentence in Australia.
An Australian team will travel to Indonesia on June 6 to negotiate the agreement, which the government hopes will be in place once appeals are exhausted.
The federal opposition has written to Jakarta asking for a presidential pardon.
Despite appearing composed throughout the trial, Corby broke down in tears as Chief Justice Linton Sirait said she was “legally and convincingly guilty” of smuggling.
Justice Sirait said Corby had admitted the bag containing the drugs was hers, and also admitted the marijuana bag was hers.
Prosecutors had sought life imprisonment.
Her sentence also includes a fine of 100 million rupiah (A$10,500).
Much of the judges’ decision appeared to be based on how Corby reacted when stopped at Denpasar airport and what she said when the drugs were discovered in her bag.
The body board bag was identified as suspicious by Indonesian customs after it was x-rayed.
One officer said Corby identified the stash of marijuana as belonging to her.
But Corby denied this in her defence, saying she opened the bag voluntarily and was shocked to find the drugs.
The judges said they took Corby’s youth and her polite demeanour into account when deciding the sentence.
After the judgement was delivered, the three justices exited the courtroom, which descended into pandemonium.
Corby pushed Indonesian officers aside and headed towards family members in the courtroom, hugging her parents and reassuring them: “It’s okay, it’s okay.”
Outside court, her financial backer Ron Bakir said her defence team would appeal against the conviction.
“We’ll take it to the highest court,” he said tearfully.
“This is a massive injustice … we’ll get her out of there if it’s the last thing we do,” he said.