The 19-year-old made his debut in Tuesday night’s 2-0 defeat by Raith Rovers.
Announcing his temporary switch to Somerset Park Hibs Sporting Director Graeme Mathie said: “Stevie has benefited from being part of Jack Ross’ first-team group for the last season and will continue to develop under the guidance of David Hopkin and Jim Duffy at Ayr United.”
Former Easter Road boss Duffy is expected to take a lead on training and match preparation in the interim so Bradley’s Ayr future does not look as uncertain as it might.
The Championship side confirmed in a brief statement: “Ayr United can confirm that we have parted company with manager David Hopkin.
“Whilst naturally the terms of our discussions with David remain confidential, we respect his views and would like to put on record our thanks for his efforts and wish him well for the future.”