One of the country's greatest ever players, Mahmoud captained the team for ten consecutive years and became an icon of Asian football.

Mahmoud's first official international goal was an equaliser in the 89th minute of the final of the 2002 WAFF Championship, which Iraq then went on to win in extra-time.

Al-Talaba won the Iraq FA Cup again and also lost the Umm al-Ma'arik Championship final to Al-Shorta again.

They also played in the 2002–03 AFC Champions League but were knocked out at the group stage; Mahmoud scored 2 goals in that tournament, both against Turkmen club Nisa Aşgabat.

[14] A few months into his spell, he got into a verbal argument with the club's manager, Rinus Israël, who subsequently refused to play him in any matches from there on.

After the 2004 AFC Asian Cup, Mahmoud joined Qatar Stars League club Al-Khor with his compatriots Haidar Jabar and Qusay Munir.

[15] Al-Khor were knocked out of the 2005 Emir of Qatar Cup at the quarter-final stage, losing on penalties to Al-Sadd after a 2–2 draw in which Mahmoud scored.

Al-Gharafa finished as runners-up of the 2006–07 Qatar Stars League, and Mahmoud's 19 goals saw him take the Golden Boot award for the first time in his career.

Mahmoud started the season by winning the 2007 Sheikh Jassim Cup and scoring 2 goals in the final, both in extra-time.

Al-Gharafa lost the final of the Qatar Crown Prince Cup, with Mahmoud scoring 2 times in the semi-final.

Al-Gharafa were knocked out of the group stage of the 2008 AFC Champions League and Mahmoud scored 1 goal in that competition.

Mahmoud joined Al-Arabi at the start of the 2008–09 season on loan and with them won the Sheikh Jassim Cup.

His campaign started off with the 2010 Sheikh Jassim Cup where Al-Gharafa were knocked out at the group stage; Mahmoud scored a hat-trick in a 5–0 win over Al-Markhiya in that competition.

In the 2011 AFC Champions League, Al-Gharafa were knocked out at the group stage, where Mahmoud scored a hat-trick against Al-Jazira.

On 8 February 2013, days after Al-Wakrah were knocked out of the Qatari Stars Cup, Mahmoud signed for Al-Sadd, joining until the end of the 2012–13 season.

Mahmoud equalled Nasser Kamile's record for goals in the Qatar Crown Prince Cup after scoring against Al-Rayyan in the semi-final on 26 April.

Mahmoud also scored in the semi-final of the 2013 Emir of Qatar Cup, and Al-Sadd reached the final, only to lose it 2–1 against Al-Rayyan.

On 15 April, he made his debut for the club against FC Ahal and scored 2 goals in the match (a header and a Panenka penalty), but could not prevent his side from being defeated 3–2 in the game.

[20] Younis Mahmoud is the only Iraqi player in history to have made the Ballon d'Or shortlist, when he finished 29th in 2007.

[22] Kaká won the Ballon d'Or that year, while Mahmoud earned two points, finishing ahead of 21 world-renowned players including the likes of Samuel Eto'o, David Beckham and Robin van Persie.

In March 2002, while many were questioning his temperament and lack of experience, coach Adnan Hamad named Mahmoud in his squad for Iraq's training camp in Italy and gave him his first start against Serie B club Cagliari Calcio and he later went on to score.

In 2006, Iraq participated in the Asian Games and reached the final but lost to Qatar; Mahmoud scored 3 goals in the tournament.

Mahmoud scored 7 goals in qualification for the 2014 FIFA World Cup but Iraq finished bottom of their group in the final round and failed to qualify.

In March 2004, Younis Mahmoud got into a scuffle with the Iraqi coaching staff led by German Bernd Stange, who left his position after the match.

He was angry at the coach after being left on the bench until the 74th minute of the draw against Palestine at the 2006 FIFA World Cup qualification.