Matafa Fofana, 21, and Rosaline Koroma, 29, had almost 9kg of low-grade meth, equating to 4.83kg of pure meth, concealed in the lining of their suitcases when they arrived in Perth in May last year.
The pair, who lived together in Melbourne, claimed they didn't know the drugs were there but were found guilty by a Supreme Court of WA jury in September.
Fofana's lawyer told the court during sentencing submissions on Monday that his client, who has a four-year-old son, had written a powerful letter but it contained no mention of remorse.
"I am sorry for being so naive and trustworthy of others," she wrote.
"I made a mistake and that mistake was to trust the wrong people."
Koroma, a refugee, also said in her letter that she was reckless and naive to "trust people", but she accepted responsibility for her actions and had shown remorse.
The prosecutor said text messages from Fofana stating she was going to Africa "for business" showed she had an awareness of her future activities.
"Both seek to maintain there was a third party who duped them," she said.
The pair will be sentenced on December 10.