Allowing frontman Clive Platt to leave Sixfields after coming to an agreement over the remainder of his contract, King also agreed one-month loan deals for Matty Blair and Sean McGinty.
Both new arrivals have versatility on their side with 23-year-old Blair (signed from Fleetwood) able to play out wide or through the middle and McGinty (20 and arrived from Sheffield United) capable of playing at left-back or in the heart of the defence.
The duo are set to make immediate home debuts against York City, Blair's former club, on Saturday afternoon in addition to new strikers Hallam Hope and Antonio German who impressed at Newport last week.