The 19-year old is the younger brother of Shola - and has made seven first team appearances in all competitions this term, scoring once - the winner at Scunthorpe in the Carling Cup.
Ameobi made his first team debut in May 2011 when he came off the bench to help Newcastle secure a 2-2 draw at Chelsea.
His England Under 21 debut came earlier this month as a substitute against Iceland and he started the next match against Belgium.
Sammy Ameobi: "It is brilliant to get this new contract signed.
"Since I have been young it has always been my dream to play for Newcastle, and it has been an amazing last year for me, making my first team debut and being involved in the squad.
"I love this club and would love to stay here for years to come."
Alan Pardew: "We are delighted that Sammy has signed a new contract.
"He is a player of huge potential and talent, and it is always great to see homegrown players come through the system at the club.
"We have already seen glimpses of what he can do, and we hope Sammy can go on and make a real impact."