Carey Lander, the keyboard player and vocalist for Camera Obscura, has died from osteosarcoma - a rare type of bone cancer.
Announcing the news on their official Facebook page, the band from Glasgow said she'd died peacefully.
They said that they had lost a friend and bandmate.
"She was left in no doubt how much you all loved and appreciated her," the band told fans.
They also thanked followers for their support and "kind words" sent to both them and Carey.
"The band, our music, and all of you who have enjoyed it over the years, meant so much to her," they said.
They encouraged fans to keep on donating to cancer charity Sarcoma UK, which Carey had been supporting.
Tracyanne Campbell, Gavin Dunbar, Kenny McKeeve and Lee Thomson say they'll keep promoting the campaign on Carey's behalf.
On Monday, donations on her JustGiving page had exceeded her target reaching around £60,000.
In her profile on the site, Carey said: "It's probably too late to help me but it would be great if we could find something in the future that means children don't have to undergo such awful treatment and have a better chance of survival.
"I've been quite fortunate in that I have been able to have periods of living something of a normal life in the last four years and to continue playing with Camera Obscura."
The musician said recording, travelling and performing despite her illness was "amazing" but that her illness was "tripping her up" again.
"I feel like it's time to tell people a bit more about it and see if I can raise a bit of cash to help others in a similar situation," she said.
Carey joined the band in 2002 and was diagnosed with osteosarcoma of the leg in 2011.
Her bandmates say their "deepest sympathy goes out to her partner Kenny and to all her family and friends".