The Antiques Dealers Fair Limited (ADFL) launched the fair in 2015 with director Ingrid Nilson at the helm.
For the most recent staging in May 2Covet became marketing partner.
It is the second fair the firm has acquired in two years, after taking over the Chelsea Antiques & Fine Art Fair in 2021.
Sophie Wood, director at the London event, will manage the Petworth fair.
Nilson said: “After eight years during which the fair has grown in stature and size, the time is right for an organisation with a bigger reach and the ability to build on what we have achieved to take the reins.”
Wood said that her team have “new and innovative ideas” to “complement what Ingrid has built”.
The fair returns for its ninth staging next May.
The ADFL now has one fair on its roster: The Mayfair Antiques & Fine Art Fair, traditionally held in January, though its return is uncertain.
Organisers are in the process of assessing interest from the trade to make it viable.
Nilson also runs The Northern Antiques Fair (the next is on September 29-October 2 at Tennants’ event space in Leyburn, North Yorkshire).