John II Palaeologus was the Margrave of Montferrat from 1338.
John was the son of Theodore I of Montferrat, with whom he was associated in the government from 1336.
He had great fortune in extending the boundaries of the margraviate against his neighbours. On 9 October 1338, he was named governor of Asti. By 1344, he had conquered Alessandria, Asti, Tortona, Bra and Alberta
On 22 April 1345, at the Battle of Gamenario, he defeated the Angevine vicar Reforza d"Angoult, who died in the battle.
With the tacit support of Luchino Visconti, John occupied Alba, Bra, Valenza and, in 1348, Cuneo. His power grew in 1355 when he accompanied the Emperor Charles IV through Italy.
At that time he received the cities of Cherasco, Novara and Pavia. By a marriage to the last titular Queen of Majorca, Isabella, he lost the support of the emperor and had to fend off attacks from imperial and Visconti troops.
This conflict concluded with restitution of territory around Pavia occupied by John to the Visconti in exchange for Visconti possessions in the area of Asti.
John lost many vassals to the Visconti. John died at Volpiano near Turin soon after composing his testament and was buried at Chivasso.