Ameobi signed for the club’s academy on 1 July 1995, but did not make his debut for the senior team until five years later, 9 September 2000, in a home game against Chelsea. He made 22 appearances for Newcastle that season, aided by injuries to then first choice strike partnership Alan Shearer and Carl Cort.
The 2002-03 Champions League seen some of Ameobi’s finest performances including a goal against Barcelona in a 3-1 defeat at the Nou Camp as well as scoring two goals against Bayer Leverkusen in a 3-1 victory.
His erratic form has earned him some criticism in the past, and although never having been claimed as a prolific goalscorer, many of his games were as a substitute. Due to injuries in the latter stages of 2005-06, Ameobi gained a regular starting place, and scored six goals in Newcastle’s last twelve Premiership games.
In the 2006 Intertoto Cup, Ameobi scored twice in Newcastle’s away tie at Lillestrøm (3-0), taking him to second place in the club’s table of leading goalscorers in European competition with twelve goals, behind only Shearer.
During the 2006–07 season, Ameobi needed a hip operation, a condition which had been plaguing him for the past two seasons. Newcastle’s shortage of match-fit first team strikers during the previous season had forced him to be postpone this surgery. The problem eventually forced Glenn Roeder to send Ameobi for surgery two months before the transfer window, making the 0–0 draw away game to Manchester City his last game and ruling him out for the rest of the season. He had made 13 appearances (three as a substitute) and scored five goals.
Ameobi and the Newcastle medical team reported his hip operation in the US was a success and that the club doctors and medical staff would work on his rehabilitation. It was originally thought that he would not be fit to play until the start of 2007-08, but his rehabilitation progressed quickly and he made a shock return with three games remaining in the season, clocking approximately 30 minutes of match action against Reading and making a further two appearances.
However, after failing to impress Newcastle manager Sam Allardyce, or Kevin Keegan on 27 March 2008, Ameobi agreed a loan deal with Stoke City until the end of the season, to help their promotion campaign. It is understood that a loan fee of around £500K was agreed and that a possible permanent transfer was also discussed subject to Stoke winning promotion. Ameobi made his debut for Stoke against Sheffield Wednesday on 29 March, the game ended 1–1. After playing for 6 games and not managing to score, Ameobi returned to Newcastle, and Stoke decided not to sign him permanently.
On 14 August, Ipswich Town manager Jim Magilton confirmed that the club were in talks with Ameobi and that the club were keen to get the deal finalised as long as Ameobi was willing to play in the second division. However, on 17 August, Ameobi failed a medical, showing hamstring problems, and the deal collapsed.
Due to long term injuries to Mark Viduka and Alan Smith, as well as shorter term injuries to Michael Owen and Obafemi Martins, Ameobi was able to start the 2008–09 season in the first team squad. He managed to score his first goal in two years for Newcastle in a 2–2 home draw with Manchester City on 20 October. After the match, interim manager Joe Kinnear praised Ameobi and backed him to kick-start his career. He followed this up with a goal in his next game away to Sunderland in a 2–1 defeat on 25 October. He signed a new deal with the club in January 2009 to keep him contracted until 2012.
He scored a penalty to mark his 50th goal for Newcastle on 1 February 2009 against local rivals Sunderland to make the final score 1–1. He scored his first ever career hat-trick in Newcastle’s first home match in the Championship against Reading on 15 August. The first two goals were diving headers, and he completed his hat-trick with a penalty, which he placed in the bottom left corner, sending the keeper the wrong way. He scored in the next game in a 1-0 victory over Sheffield Wednesday taking his tally to four goals in three games, equalling his total for the previous season. Following these early season performances he was named the Championship player of the month for August.
He got injured in Newcastle’s 4-3 win over Huddersfield in the league cup. The injury kept him out for three months but on his return he scored against Coventry with a left footed strike from the edge of the box.
Nigerian-born Ameobi has earned 20 England’s U21 caps over a 3 year period, scoring 7 goals.