The two deals put an end to any speculation about their futures, with rumours suggesting Tottenham were eyeing a move for Krul whilst Coloccini has been linked with one last big move this summer.
Both Krul and Coloccini were paraded at a press conference held ahead of tomorrow's crunch match against local rivals Sunderland in the Tyne-Wear derby.
Krul has put pen to paper on a new deal which will see him remain on Tyneside until 2017, whilst Coloccini will be at the club until 2016.
Both deals become active on the 30 June this year, and will be greeted enthusiastically by the Geordie faithful, who have been impressed by the form the team have shown in reaching sixth place in the Premier League table.
The duo have been instrumental in their rise up the table, and manager Alan Pardew was particularly thrilled that they would be extending their stay in the North East.
He said: "These are two fantastic deals for the club and we are all absolutely delighted.
"To secure new contracts for Fabricio and Tim, two pivotal players at the club, is terrific news for all concerned, not just ahead of the derby but for the long-term future of the club.
"It underlines the importance that we as a club place on building and retaining top class talent, and it demonstrates the intent of Newcastle United to be major players in the Premier League.
"I would also like to place on record my thanks to [owner] Mike [Ashley] and [managing director] Derek [Llambias] for their hard work and continued financial backing in ensuring these deals were completed.
"We now turn our attentions to tomorrow's big game, boosted by this news - which I hope gives our incredible fans a huge lift too - and with the confidence to really make this a season to remember."
Pardew also revealed that the negotiations for the new contracts didn't finish until yesterday evening, and that the two extending their stay offers the club "security."
Captain Coloccini added: "We can now win something for the fans, I hope to do that in these five years."
He then turned his attentions to tomorrow's pivotal Tyne-Wear derby by saying: "I hope we can win the game and it is a happy Sunday for the fans!"
Krul pointed to this season's performance so far as firm evidence that the club are going places, and said this was a huge factor behind his signing a new contract.
The Dutchman said: "We are heading the right way now.
"I owe the club and manager a lot, they gave me a chance."
Magpies duo Ryan Taylor and Danny Simpson, who has yet to sign a new deal at the club himself, were both quick to congratulate their team-mates on the news.
Taylor wrote on Twitter: "Good to see the Skipper an the 1 of the best Goalies in the league committing to the club today. #GoodTimes."
Simpson also used the social networking site, saying: "Buzzin 4 my teammates n Newcastle that Tim n Colo have signed long term contracts! Quality players... Follow @TimKrul n show him the love he deserves."