The 21-year-old Northern Ireland international has made five starts and one substitute appearance for the Blues since joining them on an emergency loan at the beginning of last month.
His initial spell ended after Easter Monday's 3-2 defeat to Wolverhampton Wanderers but he will now stay on for their final six games of the campaign.
Ferguson struck his first senior goal during City's 4-0 victory at Crystal Palace on Good Friday.
Manager Lee Clark said: "We think Shane's a terrific little player and he's a great kid; we're delighted that we'll have him for the rest of the season.
"I think the deal has benefited us, Newcastle and Shane. He's brought quality, tenacity, speed and energy and he puts in quality deliveries. You've also got to remember just how young he is as well."