2007 | European Union Amateur Championships

In 2007, Barnes competed at the EU Championships in Dublin. He had his medal hopes crushed however when he suffered an eye injury. With bleeding found behind his retina, Barnes was forced out of the competition.^[2]

2007 | World Amateur Championships

At the World Championships in Chicago Barnes missed out on a bronze medal after he was defeated by China's Zou Shiming in the quarter-finals, Zou went on to win the gold medal. ^{[citation needed]}

However, Barnes qualified for the 2008 Olympics by virtue of getting to the quarter-finals.^[3][4][5]

• 1st round – defeated Choi Jon Chuk North Korea 33–19
• Round of 32 – defeated Sadegh Zade Faraj Iran 30–10 (RSCO)
• Round of 16 – defeated Kenji Ohkubo Japan 24–6
• Quarter final – lost to Zou Shiming China 8–22

2008 | European Union Amateur Championships

In 2008, Barnes returned to EU Championships, this time in Cetniewo, Poland.^{[citation needed]}

Barnes made it to the final where he lost to Hungarian fighter Pál Bedák. The silver medal was enough to secure his place at the Summer Olympics.^{[citation needed]}

2008 | Olympic Games

Barnes won Ireland's inaugural medal, at the 2008 Summer Olympics, by winning his quarter final bout in the light flyweight division. Barnes won a bronze medal after he was defeated in a second match with Shiming Zou in the semi-final, in a match where replays showed some of Barnes landed punches counted as points for Zou.^{[citation needed]}

• Round of 32 – bye
• Round of 16 – defeated José Luis Meza  Ecuador 14–8
• Quarter final – defeated Łukasz Maszczyk  Poland 11–5
• Semi-final – lost to Zou Shiming  China 0–15

2010 | European Amateur Championships

On 12 June 2010, Barnes won the gold medal in the light flyweight division at the 2010 European Amateur Boxing Championships. Barnes, a 4–1 winner over Azerbaijan's Elvin Mamishzade, was 1–0 up at the end of the first round, 3–1 ahead at the end of the second and sealed the victory with a final point in the third for 4–1.^[6]

2010 | Commonwealth Games

Barnes represented Northern Ireland at the 2010 Commonwealth Games.^[7] He won the gold medal, defeating Namibia's Jafet Uutoni 8–4 in the final.

• Round of 16 – defeated Iain Butcher  Scotland 4–2
• Quarter final – defeated Andrew Moloney  Australia 5–3
• Semi final – defeated Amandeep Singh  India 5–0
• Final – defeated Jafet Uutoni  Namibia 8–4

2012 | Olympic Games

At the 2012 Summer Olympics he defeated Thomas Essomba from Cameroon 15–10 then beat India's Devendro Singh in his quarter-final bout to guarantee himself at least another bronze medal. In doing so, he became the inaugural Irish boxer to win medals at two consecutive Summer Olympics.

For the semi-final, Barnes once again drew Chinese superstar Zou Shiming, who had defeated Barnes in the 2008 semi-finals before taking gold. Barnes gave a fearless performance against the three time World champion, with the judges tying them 15–15 on the scorecards, only for Barnes to lose via a 45–44 countback. Shiming once again went on to win gold.^[8]

• Round of 16 – defeated Thomas Essomba  Cameroon 15–10
• Quarter final – defeated Devendro Singh  India 23–18
• Semi-final – lost to Zou Shiming  China 15–15 / 44–45 (CB)

2014 | Commonwealth Games

As captain of the Northern Ireland boxing team in 2014 at Glasgow, Barnes led the way by winning gold in the flyweight division defeating India's Devendro Singh. It was the first time a Northern Irish boxer had successfully defended a Commonwealth title.^[1]

The tournament was held at the Scottish Exhibition and Conference Centre. 17 boxers from 17 nations took part.^{[citation needed]}

After the competition, Barnes accepted an honour, the MBE, in the 2015 New Year Honours, for services to boxing and the community in Northern Ireland.^[9][10]

2015 | World Series of Boxing

Barnes competed in the WSB for the 2014–2015 season. Along with Michael Conlan, he was drafted by Italia Thunder. His first fight came against Magomed Ibiyev of the Baku Fires, in Baku. Barnes won with a 49–46, 49–46, 50–44 unanimous decision.^[11]

His second fight was another win, this time over Anthony Ortiz as Italia Thunder met the Puerto Rico Hurricanes. The judges scored it 48–47, 49–46, 49–46 as Barnes took another unanimous decision win.^[12]

The Hussars of Poland were next up, in Konin. Barnes continued his perfect start to the season with a landslide 50–45, 50–43, 50–45 victory over Sebastien Jagodzinski.^[13]

His record for the season went to four wins with four unanimous decisions, when he defeated Kazakh fighter Temirtas Zhussupoy of the Astana Arlans in Kazakhstan.^[14] His next fight was in Maiquetia, with a split decision win over Caciques de Venezuela's Finol Rivas. The judges scored the bout 49–45, 49–45, 47–48 in favour of Barnes.^[15]

2016 | Olympic Games

Barnes was also chosen to be the bearer of the Flag of Ireland Tricolour at the 2016 Summer Olympics, something that Barnes considered an "incredible honour".^[16][17] At the 2016 Summer Olympics Barnes was defeated 2–1 by Samuel Carmona in the round of 16.^[18]

Provincial and National Titles

Barnes lost the Ulster title in 2005, 2006 and 2007. He faced Jimmy Moore from Limerick in each of his national finals being runner up in 2006 but winning the All-Ireland title in 2007 and 2008.^[19][20][21]

Barnes vs. Slavchev

After his amateur success, Barnes turned professional and made his debut as a bantamweight against Stefan Slavchev on 5 November 2016. Slavchev lifted Barnes into the air during the fourth round, so Barnes won the bout via disqualification.^[22]

Barnes vs. Rosales

On 18 August 2018, Barnes challenged Cristofer Rosales for his WBC world flyweight title. Barnes got off to a fast start, but was introduced to Rosales' power early in the first round. In the fourth round, Rosales caught Barnes with a vicious right-hand uppercut to the solar plexus. Barnes fell on the canvas and wasn't anywhere close to beating the count, which meant a KO victory for Rosales.^[23]

Barnes vs. Harris

On 11 October 2019, Barnes faced Jay Harris. Barnes was dropped by his oponnent both in round three and round four. The latter proved to be the final one, as Barnes was not able to beat the count, and Harris was awarded the KO victory.^[24]

Retirement

In November 2019, Barnes announced his retirement from professional boxing.^[25]