Carl Sargeant, a member of the Welsh Assembly, quit his role as Wales’s communities secretary last week.
Today the 49-year-old father of two was found dead at his home in Connah’s Quay, North Wales.
Jeremy Corbyn said he was shocked by the news of Mr Sargeant’s death.
The Labour leader said: “This is terrible and deeply shocking news. My thoughts and profound sympathy are with Carl’s family, friends and colleagues.”
His deputy Tom Watson added: “I campaigned with Carl for many years. He was a powerful voice for working people and Wales. He put community at the heart of his politics and was respected by his constituents for it. My love and prayers are with Carl’s family today. This is a tragedy beyond words.”
Mr Sargeant, who served in the Welsh Assembly for 14 years, was suspended from the party by First Minister Carwyn Jones last Friday.
He was accused of unspecified misconduct towards women, reportedly involving sexual allegations.
Mr Sargeant’s wife Bernie, 48, and children Lucy, 25, and Jack, 23, today spoke of their grief at his death.
They said in a statement today: “Carl was a much loved husband, father and friend. He wasn’t simply a part of our family. He was the glue that bound us together. He was the heart of our family. We loved him so very much.
“He was the most kind and caring husband, father, son and friend.
“We are devastated beyond words, and we know our grief will be shared by all those who knew and loved him.”