Members have refused to return to the church until she is reinstated.
Perth's oldest Catholic choir has been thrown into upheaval on the cusp of one of the most important days on the church calendar.
At least 13 members of the St Mary's Cathedral choir have vowed to boycott Christmas mass and other events following the sudden departure of musical director Jacinta Jakovcevic.
The walkout has forced the Catholic Archdiocese to seek replacement musicians at short notice and re-ignited concerns among parishioners about transparency within the church.
Ms Jakovcevic was removed from her post in October after almost 24 years overseeing the music program.
Her dismissal came as a shock to many within the church community, which is demanding answers over how the decision was reached.
"Has there been a genuine redundancy? That's the question for me," parishioner Benna Masbate said.
"Redundancy means the employer no longer requires that person's job in any capacity. That has not happened here.
"Jacinta's job is being done right now. Someone else is doing it."
Members leave church
Ms Jakovcevic was made redundant following a review of St Mary's musical program commissioned by the Dean of the Cathedral, Father Sean Fernandez.
The review also recommended three new roles be created, with the former director told she could apply for one of those positions.
Ms Masbate gave up her roles within the Cathedral in the wake of the removal of Ms Jakovcevic, while her teenage son Michael has also walked away from the choir.
She acknowledged Fr Fernandez was within his rights to make changes to the musical program, but said nobody within the organisation had been asked to participate in the review.
"The way in which it's been done reeks of a non-consultative manner... and due process has not been met," she said.
"Music is not his strength. So I ask 'where do your standards come from? Who are the experts you consulted? Who did you reach out to?'
"We feel like we're banging our heads up against a very formidable wall."
A Christmas boycott
The unrest among choristers has led to a growing boycott of St Mary's just days before some of the biggest events of the year.
With many now refusing to perform at Christmas mass, musicians from other parishes have been recruited to help fill gaps.
Those changes haven't gone unnoticed, according to chorister Tom*, who was among those to join the walk out.
"Unfortunately some people have been directing that towards the musicians who've replaced us, and we don't want that to happen."
For Tom, the decision to support Ms Jakovcevic has come at a significant financial cost.
"It's been relatively severe. Particularly at this period where there would be a lot of masses a lot of services" he said.
"Now that's not coming in I've had to scramble to get more shifts in my casual job. It'd be similar for others in the choir whose main source of income is the church."
Tom said some 300 church musicians from across Perth had vowed not to perform at St Mary's.
Concerned choristers have also established a website, Every Voice Matters, to share their concerns.
One of the founders of the site, who did not want to be named, said the dismissal of Ms Jakovcevic had left many people uneasy about their own futures.
St Mary's responds
St Mary's said it would not comment on individual employees.
"Regrettably over the past few weeks, information has been circulated about the recent Music Programme Review which is inaccurate," the church said in a statement.
"St Mary's.... seeks to work collaboratively to achieve an exciting vision for the Music Program that has been shared, which will further enrich the St Mary's Cathedral, Perth, community and beyond."
The Cathedral said its Masses of Christmas would include a program of music featuring both long-standing and more recent choristers and musicians.
Ms Jakovcevic declined to speak to the ABC for this story.
The ABC understands she is seeking legal advice regarding her dismissal and has no involvement with Every Voice Matters or the choir boycott.
Tom said he hoped the efforts to restore Ms Jakovcevic to her position would be successful and he had no regrets about his stance.
But he said not taking part in Christmas mass would be difficult.
"It's something I look forward to and this'll be the first time I haven't done it in more than a decade," he said.
"Singing and playing music is so special and moving and it's something I'll be missing.