This is described in some considerable detail in the Star Trek Deep Space Nine - Technical Manual. In short, the wormhole orbits the local Bajoran Star (known as Bajor-B'hava'el) at an orbital distance of some 300 million kilometres.
The guide also offers a handy map in case you plan to travel there. The thick white line is the Denorios Belt, the thinner yellow line is the wormhole's orbit.
The wormhole terminus exists in the star system's distant plasma
torus known as the Denorios Belt, some three hundred million
kilometers from the sun. Bajor-B'hava'el.
The basic mechanics and properties of the wormhole have been studied
thoroughly since 2369. when Deep Space 9 was first moved outward from
its orbit around Bajor. It is known that the Bajor terminus moves with
the Denorios plasma field in an orbit about the sun with a period of
13.5 years. The average orbital period of the belt is faster. 13.1 years, creating periodic density waves that can upset station
operations. The orbital plane is inclined 38 degrees to that of Bajor.
but only 11.5 degrees to that of the ecliptic created by Bajor IX. the
largest gas giant planet in the system. Historical back-trace
calculations indicate that the subspace inversion event each 50.23
years has been visible from Dahkur Province for at least the last
thirty-five hundred years, and possibly as far back as thirty thousand
years, with corrections for minor perturbations, axial precession,
and tidal slowing.