The Saints have endured a difficult start to their Aviva Premiership campaign and currently sit in ninth place in the standings, with just two wins from their first six games of the season.
Northampton decided to axe attack coach King, who had been part of the management team that helped Saints win the Premiership and European Challenge Cup back in 2014.
Mallinder has admitted it was a tough decision to allow King to leave but felt it was time for a change at Franklin's Gardens.
"This is my 10th season and actually we haven't made many changes to the coaching set-up," said Mallinder.
"We made one a few years ago and went on to win the Premiership and a European competition. Hopefully this little change will do the same."