Lyra McKee, who was murdered in Derry on Thursday night, was a talented journalist and writer "with her whole career in front of her".
Belfast-born Lyra, 29, had earned raved reviews after appearing as a guest speaker at the TEDxStormont event at Parliament Buildings in 2017.
Since her senseless killing on the streets of Creggan, there's been Lyra McKee murder: Easter parade in Derry cancelled as Saoradh issue statement to someone of "courage and integrity".
Michelle Stanistreet, NUJ general secretary, said: "A young, vibrant life has been destroyed in a senseless act of violence.
"Our thoughts are with her partner, family and many friends and colleagues. A bright light has been quenched and that plunges all of us in to darkness."
For many people, their first introduction to her work was her piece about growing up gay in Belfast - Letter To My 14 Year-Old Self - which was subsequently turned into a powerful short film, the union said.
Angels With Blue Faces, a non-fiction book about the Troubles murder of South Belfast MP Rev Robert Bradford, was released in 2018.
Faber is due to publish her book, The Lost Boys, in 2020.
Lyra McKee murder: Easter parade in Derry cancelled as Saoradh issue statement
Seamus Dooley, NUJ assistant general secretary, said: "Lyra McKee was a journalist of courage, style and integrity.
"She was a woman of great commitment and passion.
"I have no doubt that it was that commitment which led to her presence on the streets of the Creggan last night, observing a riot situation in the city."
Irish President Michael D Higgins said: "The people of Ireland will have heard with both shock, outrage and great sadness of the killing of the young journalist Lyra McKee in Derry last evening - a woman of talent and commitment, who was shot exercising her profession."
Lyra McKee named as victim of Derry Shooting
Ann Travers, whose sister Mary was murdered by the IRA in 1984, said Ms McKee was a kind and gifted person.
Amnesty International said it was "utterly devastated" by the death of Ms McKee, who was to appear at one of its events in Belfast next month about the dangers of reporting violent conflicts.
Patrick Corrigan, Northern Ireland programme director of Amnesty International, said: "Lyra was a great young journalist, whose commitment to truth was absolute and whose laughter could light up a room.
"Lyra McKee was one of those courageous seekers after truth, with a life ahead of her and so much to give.
"Our thoughts are with Lyra's partner, her family and many friends."
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