The 37-year-old left Tynecastle in 2020 after a five-year spell with the club, including a season where he was allowed to take the reins at League Two side Cowdenbeath.
He spent the 2020/21 season working as an assistant to David Martindale at Livingston but left the West Lothian side to take up a new opportunity. It was reported he was heading to Easter Road and a reunion with manager Jack Ross whom he worked with briefly at Hearts. However, according to the Evening Telegraph, Fox knocked back the offer in order to become assistant manager to new boss Tam Courts at Tannadice.
The head of tactical performance for the club’s youth academy has been selected as the successor to Micky Mellon, who left United after just one season in charge last month.