Van Mildert played an important role in the development of the design of Flemish Baroque religious furniture.
[1] When in 1633 Rubens was elected dean of the Antwerp Guild of Saint Luke he was allowed to leave the actual administration in the hands of van Mildert.
[4] His son Cornelis and his son-in-law Gerard van Opstal completed some of the works left unfinished at the time of his death.
[5][6] From about 1617 onwards van Mildert received multiple large commissions as a sculptor-architect and maker of small-scale architectural stone church furniture.
He thus became the main competitor of the workshop of the brothers Hans and Robert Colyns the Nole that had dominated the Antwerp market from the beginning of the seventeenth century.
In 1618 he executed a black and white marble altar made for the Chapel Church in Brussels based on a design by Rubens.