Mills joined Fleet in June from Dartford`s league rivals Whitehawk.
He scored 102 goals for the Hawks after joining the club in 2012, having previously had spells with clubs including Peterborough United and Torquay United.
Dartford manager Tony Burman told his club`s official website: “Danny was a player I have always been interested in and once he was available for loan I knew I needed to try and bring him to the club.
“I am delighted to have a player of Danny’s calibre added to the squad for this very imporatant period of any season.”
Mills goes into the squad for tomorrow’s game at Poole Town.