Buckley’s first cousin Brendan Fuller was among her family members who stayed up late to see her collect her award on TV.
He told BBC News NI that witnessing her “mentioned in the same category as Julia Roberts” made him realise how far she had come.
“I remember watching Ocean’s Twelve with Jessie when I was 12,” Fuller recalled.
“And seeing her then being nominated in the same category, and then winning the category ahead of a Hollywood icon… we’re just so, so proud of her.”
As a schoolgirl, Buckley performed in stage productions at Ursuline Secondary School in Thurles, County Tipperary.
“From the moment she took to the stage in the school hall here in the Ursuline, it was clear Jessie had a special talent,” the school said in a statement on Monday, external.
“It is an inspiration for Ursuline students to see one of their own recognised on the global stage.”
Teachers at RIAM in Dublin are also “very proud” of their former pupil, according to the academy’s head of artistic programming, Ciara Higgins.
However, she stressed Buckley had “carved her own pathway” and achieved success “on her own terms”.
“I don’t think we can claim any of that, but it’s just wonderful to be a little of a part of that Golden Globes history and fingers crossed, a little bit of that Oscar history in the weeks ahead,” Higgins added.