Brisbane woman Alana Miles was arrested at Santa Cruz airport in March 2013 after she was found with a backpack containing cocaine.
She has been held in Bolivia's Santa Cruz prison since that time and only sentenced this week for the crime. It was not clear when she was charged.
Upon arrest, Miles denied knowledge of the bag's contents.
Sister Kylie Miles told NITV the family was relieved to finally have an outcome.
"At least we know now and we’re able to sleep better," she said.
"In the first instance it was just relief because we didn't know before, and there's so much more we don’t know but at least we've got something that's solid."
Kylie told NITV her sister had been advised to plead guilty to increase her chances of a pardon.
"Now what we’re waiting for is the papers to be sent for her sentencing and then she can apply for a pardon," she said.
But she said the plea had not been an admission of guilt.
"She pled guilty to get home, most definitely."
When asked why she thought Australian media had taken little interest in her sister's case, she was unsure.
"It's a bit of a mystery to me," she said. "Considering Schapelle's story was about drugs and the Bail Nine about drugs. I don't see any difference, other than it's not Bali."
In a statement, the Department of Foreign Affairs and Trade says the Australian Embassy in Lima and the Australian Honorary Consul in La Paz, Bolivia were providing consular assistance to Ms Miles and were also in regular communication with the woman's family.
