Alo-Bridget Namoa and Sameh Bayda, both now 22, were found guilty in 2018 of conspiring between December 8, 2015 and January 25, 2016 to do an act in preparation for a terrorist act.

Namoa, who was jailed for three years and nine months with a minimum term of two years and 10 months, is currently on parole.

The NSW Supreme Court jury was told the then-18-year-olds married in an Islamic ceremony before Bayda's planned "attack" on non-Muslims on New Year's Eve 2015.

The NSW Court of Criminal Appeal on Monday dismissed Namoa's conviction appeal.

Neither she nor Bayda went into the witness box at their trial, but both gave evidence at their sentence hearing.

He testified that contrary to what he understood Namoa believed, he didn't plan to die carrying out a New Year's Eve attack and sought to manipulate her into thinking it was more significant and dangerous than what he planned.

Bayda said he only told Namoa he was carrying out a suicide attack to get her to feel sorry for him and accept his marriage proposal.

The Appeal Court rejected a claim this was "fresh evidence" which demonstrated there had been a miscarriage of justice.

Namoa had clearly agreed with Bayda in the making of preparations for a terrorist act and there was no "significant possibility" she would have been acquitted based on Bayda's sentence hearing evidence, the judges said.

They also dismissed a claim that the trial judge erred in dismissing her application for a permanent stay of the charge against her based on a claim about immunity from prosecution for a conspiracy involving a husband and wife.

Australian Associated Press