By early 1809 he was seriously ill. He had long suffered from kidney stones, which also lodged in the bladder, causing him great pain. He died at Soho House on 17 August 1809. He was buried in the graveyard of St. Mary's Church, Handsworth, in Birmingham – the church was later extended over the site of his grave. Inside the church, on the north wall of the sanctuary, is a large marble monument to him, commissioned by his son, sculpted by the sculptor John Flaxman. It includes a marble bust of Boulton, set in a circular opening above two putti, one holding an engraving of the Soho Manufactory.