The Serbian striker had an impressive spell in west London during the second half of last season, as he scored on 12 occasions as he helped the 'Cottagers' gain promotion to the Premier League via the Play-Off Final, and went on to represent his country at the World Cup.
Mitrovic had a difficult time on Tyneside, while his talent has never been doubted by the club or their fans, issues with discipline have been a constant issue for the forward.
Manager Rafa Bentiez was particularly unimpressed with his disciplinary record, and it had been apparent for a while that the player was not in the Spaniard's plans.
'Sky Sports' report that a bid from the newly-promoted side has been accepted by Newcastle, believed to be in the region of £20 million.
It is a deal that suits all parties, as the 'Magpies' look to finance further transfers to add to the 5 they have already managed to secure.
However, many Newcastle fans will feel as though a talented player with bags of potential has just slipped out of their grasp.