The singer, 52, was surrounded by her family when she passed away earlier today (4 July) following a three year battle with the disease.
A spokesperson for Bernie says: "Bernie passed away peacefully this morning with all of her family around her.
"The entire family are devastated to have lost beloved Bernie, a wonderful wife, adoring mother and loving sister, she is irreplaceable. They kindly ask people to respect their privacy at this difficult time."
Chris Askew, Chief Executive of Breakthrough Breast Cancer, added: "We're deeply saddened by the news that our wonderful supporter Bernie Nolan has passed away.
"Bernie was a truly inspirational woman who became a part of the Breakthrough family after her first breast cancer diagnosis in 2010. We were devastated to hear that her breast cancer had returned in 2012. Her spirit and determination to try and fight the disease spurred us all on and will continue to do so. Our thoughts are with Bernie's husband, daughter, family and friends at this time."
Bernie revealed in April 2010 that she had been diagnosed with breast cancer, which had spread to her lymph nodes. Following a mastectomy and chemotherapy she was given the all clear.
Sadly, however, the cancer returned in October last year and Bernie was told it was incurable.
Bernie, who found fame along with her sisters in the 70s, leaves behind her husband Steve and daughter Erin.