Now, the 15-year-old has made history as the youngest-ever player to appear in a Premier League match, coming on in the dying embers of the Gunners' 3-0 win over Brentford on Sunday.
Nwaneri replaced Fabio Vieira in added time at the Brentford Community Stadium, with Mikel Arteta claiming that he had a "gut feeling" about the 2007-born attacking midfielder.
Nwaneri becomes the latest in a long line of teenagers to appear in the Premier League before their 18th birthday, and here, Sports Mole counts down the 10 youngest players in the history of the tournament.
10. Jack Wilshere - 16 years, eight months, 12 days
Prior to Nwaneri's debut, Jack Wilshere previously held the record of being Arsenal's youngest-ever player in the Premier League, coming on at the age of 16 against Blackburn Rovers in September 2008.
With Arsene Wenger's side comfortably 3-0 up at Ewood Park, Wilshere was brought on to replace Robin Van Persie in the 84th minute and serves as a timely reminder of the English starboy who never quite fulfilled his potential.
After calling it quits on a short-lived and injury-hit career earlier this year, the 30-year-old has since returned to London Colney to take up the role of manager for the club's Under-18s.
9. Jack Robinson - 16 years, eight months, seven days
Beating Wilshere by a mere five days, former Liverpool youngster Jack Robinson was also just 16 years of age when he made his Premier League bow for the Reds against Hull City in May 2010.
With nothing left to play for on the final day of the season, Rafael Benitez was not averse to fielding a second-string side for that 0-0 draw, as Robinson replaced Ryan Babel in the 87th minute.
The centre-back would make 10 more appearances for Liverpool before leaving in 2014, and he can now be found marshalling the backline at Sheffield United, playing 17 Premier League games in 2019-20 and 2020-21.
8. Reece Oxford - 16 years, seven months, 24 days
Starting for the visiting team at the Emirates Stadium and running out 2-0 winners would be a monumental achievement for most players, let alone a 16-year-old Reece Oxford.
The now-23-year-old was fielded from the first whistle by Slaven Bilic on the opening day of the 2015-16 season, where goals from Cheikhou Kouyate and Mauro Zarate saw West Ham United clinch a memorable London derby success over Arsenal.
Oxford played 79 minutes of that victory at the Emirates, and following a couple of loans to the Bundesliga, he has now found his new home in Augsburg.
7. Rushian Hepburn-Murphy - 16 years, six months, 14 days
Another player to come out on the correct end of the scoreline during his Premier League debut was Rushian Hepburn-Murphy, who was just 16 when he made a seven-minute cameo in Aston Villa's 4-0 win at Sunderland in March 2015.
Christian Benteke and Gabriel Agbonlahor had both scores braces in the first half before Tim Sherwood turned to Hepburn-Murphy, who remains the Lions' youngest-ever player in the Premier League.
The striker would never hit the heights of Benteke or Agbonlahor at Villa Park and left for Cypriot side Pafos FC in 2020, but he returned to England earlier this summer to join Swindon Town.
6. Jose Baxter - 16 years, six months, nine days
The first player on this list to suffer defeat on his Premier League debut, Jose Baxter tried and failed to help Everton over the line in a 3-2 defeat to Blackburn on the first day of the 2008-09 season.
A fresh-faced 16-year-old, attacking midfielder Baxter came on for the final 11 minutes at Goodison Park with the score at 2-2, but David Moyes's decision backfired as Blackburn scored a 93rd-minute winner through Andre Ooijer.
After being released by Everton in 2012 - although he briefly represented the Under-21s in 2017-18 - Baxter plied his trade for Plymouth Argyle, Sheffield United, Oldham Athletic and Memphis before hanging up his boots last year.
5. Aaron Lennon - 16 years, four months, seven days
Such is Aaron Lennon's longevity that the England winger was around back in the Glenn Hoddle era of Tottenham Hotspur, making his Premier League debut all the way back in 2003 against the Lilywhites for Leeds United.
Lennon was a 77th-minute substitute for Mark Viduka in that 2-1 defeat before earning a move to Tottenham in the summer of 2005, eventually totalling 30 goals and 79 assists in 364 games for the North London club.
Despite featuring regularly for Burnley in the 2021-22 Premier League, the 35-year-old is now without a club following his exit from Turf Moor, but he is seemingly not done and dusted at the top level just yet.
4. Izzy Brown - 16 years, three months, 27 days
Sharing striking similarities with Baxter's debut, former West Bromwich Albion youngster Izzy Brown was also a mere 16 years of age when he made his top-flight bow in a 3-2 loss to Wigan Athletic in 2013.
The striker was a late substitute for Youssouf Molumbu but could not influence the game in the dying embers, although his rise was enough to earn him a move to Chelsea later that year.
As has been the case with a plethora of Blues youngsters, Brown made just the one appearance for Chelsea and was loaned out countless times, but he is now a free agent after departing Preston North End this summer.
3. Matthew Briggs - 16 years, two months, seven days
Final-day Premier League showdowns at Middlesbrough's Riverside Stadium will be best remembered for the 8-1 thrashing inflicted upon Manchester City in 2008, but history was written one year beforehand.
Fulham also went down to Boro on the final day in 2006-07 - losing 3-1 - but 16-year-old Matthew Briggs became the Premier League's youngest-ever player after coming on for Moritz Volz in the 77th minute.
Briggs - who held the record for 12 years - would sit his GCSE Exams just 24 hours later, and the Guyana international can now be found plying his trade in the Southern League Premier Division South with Gosport Borough.
2. Harvey Elliott - 16 years, 30 days
Another Cottagers starlet to hold the distinguished honour of being the Premier League's youngest-ever player, Harvey Elliott broke Briggs's record when he debuted for Fulham in May 2019 against Wolverhampton Wanderers.
Scott Parker's side lost 1-0 on the day as Elliott came on for the final two minutes, and such was his talent that Liverpool quickly moved to sign Elliott just a few months later.
Still only 19 years old, Elliott has now established himself as a key member of Jurgen Klopp's first team squad and earned himself a bumper new contract at Anfield back in August.
1. Ethan Nwaneri - 15 years, five months, 28 days
A chorus of "You've got school in the morning" rang out around the Brentford Community Stadium when Nwaneri came on for Arsenal on Sunday. Queen Elizabeth II's funeral and the coinciding state funeral meant that such chants were inaccurate, but that took nothing away from the teenager's historic moment.
Quickly demonstrating his class at Under-18 level, Nwaneri was promoted to Under-21s training for Arsenal, whose academy manager Per Mertesacker gave Arteta glowing reports from his time at youth level.
Martin Odegaard's injury opened up a spot for Nwaneri to travel with the first-team squad for the trip to Brentford, and Arteta felt it appropriate for the Englishman to experience a taste of top-flight football with his dominant side 3-0 to the good.
Arteta has warned optimistic fans that Nwaneri may need to take a "step back" before taking another step forward, but there is every reason for Gooners to get excited about this history-making starlet, and it is difficult to see his record being broken anytime soon.