The Pulp bassist died after three months in hospital, although a cause of death has not been revealed.
Katie posted a tribute to his Instagram page announcing his death.
She shared a black and white photo of Steve smiling.
It said: “After three months in hospital, fighting with all his strength and determination, we are shocked and devastated to have said goodbye my brilliant, beautiful husband, Steve Mackey.
“Steve died today, a loss which has left myself, his son Marley, parents Kath and Paul, sister Michelle and many friends all heartbroken.
“Steve was the most talented man I knew, an exceptional musician, producer, photographer and filmmaker. As in life, he was adored by everyone whose paths he crossed in the multiple creative disciplines he conquered.
“I would like to express my heartfelt thanks to all the NHS staff who worked tirelessly for Steve. He will be missed beyond words.”
The bassist was part of the rock group Pulp, which he joined in 1989, which was best known for its hit Common People.
He also produced music for big names in the music industry including Florence + the Machine and M.IA.