When the conflict's eastern front settled, Boniface had to face the advance of the Dukes of Savoy.
Boniface signed a treaty of non-belligerence, and had his niece Bianca married to Duke Charles I of Savoy.
This decision was spurred by the assassination of Scipione Palaiologos, the illegitimate son of John IV of Montferrat who tried to gain the throne, at Casale Monferrato by his relative Ludovico II, Marquis of Saluzzo, who was also a candidate to the succession.
Boniface sided the House of Savoy in the war against Saluzzo of 1486, and occupied several lands in the Langhe belonging to Ludovico II.
At his death, Boniface was succeeded by his eldest son William IX (1486–1518), who became Marquis of Montferrat between 1494 and 1518.