Šimunić was born inCanberra, Australia, toBosnian Croat immigrants fromOtigošće nearFojnica.[4] He received early football training atCroatia Deakin in his hometown of Canberra before attending theAustralian Institute of Sport program.[5] The defender broke into theMelbourne Knights first team as a teenager in the1995–96 season and ended it with a championship medal and 1996 NSL Youth Player of the Year award. Šimunić scored his first goals the following term, three in 14 outings, before moving to Europe to joinHamburger SV in 1997.[1]
Šimunić moved toHertha BSC in 2000 after having fallen out with Hamburg coachFrank Pagelsdorf. He later became an integral member of a team that enjoyed occasional forays in theUEFA Cup. At the end of the2008–09 season, Šimunić was named the best centre-back in theBundesliga byKicker.[6] Hertha finished in fourth place that season, with a defence that conceded only 41 goals, tied for third in the league withVfL Wolfsburg.
In the beginning ofhis second season with the club, Šimunić established himself as the first-choice centre-half and regular starter. He played the full 90 minutes in each of Dinamo'sgroup stage matches in the2012–13 UEFA Champions League.
On 14 December 2014, Šimunić officially retired from professional football.[8][9]
Šimunić was educated at theAustralian Institute of Sport (AIS). He was eligible to play forAustralia but opted to play forCroatia. After obtaining dual citizenship in October 2001, he made his international debut in Croatia's friendly match againstSouth Korea on 10 November 2001. He did not play in any of Croatia'squalifiers for the2002 World Cup, but was given a place in thesquad for the finals after an injury forcedIgor Tudor out. Šimunić played all three of Croatia's matches in South Korea and Japan. He also played at the2004 Euros, the2006 World Cup and the2008 Euros, performing well in the latter tournament.
In a well-publicised incident, Šimunić was sent off in Croatia's final 2006 World Cup match against Australia. Having picked up his first booking in the 61st minute, he was given a second yellow card by English refereeGraham Poll for his tackle in the 90th minute. Poll committed a rarely seen blunder and forgot to dismiss Šimunić from the pitch. Three minutes later, at the very conclusion of the match, Šimunić remonstrated with Poll and received a "third" yellow card, this time followed by a red card.FIFA initially noted all three bookings in its match report, before later removing the 90th minute (second) booking. This prompted the removal of Poll from the referee pool for theknockout stages of the tournament. Shortly after the World Cup, Poll retired from refereeing international games, citing this game as a direct cause. Upon the release of his autobiography in 2007, Poll revealed that upon booking Šimunić for the second time, he had erroneously recorded him as "Australia #3" (who was defenderCraig Moore), due to Šimunić's Australian accent.
Šimunić was known for great football technique, despite having been a centre-half. His national teammateNiko Kranjčar had said of him, "In training, he does feints likeRonaldinho."[10]
Šimunić was involved in a controversy following a 2–0 win for Croatia againstIceland inZagreb on 19 November 2013. He was accused offascist sympathies for having directed the crowd in a chant following the game. The use of the salute "Za dom!" (For [the] homeland!), with the fans responding "Spremni!" (Ready!), was identical to the salute used by the fascistUstaše movement inCroatia during World War II.[11]
He defended his actions saying that he was driven by "love for his Croatian homeland". After the match, Šimunić responded to his critics: "Those who are bothered by those shouts should studyhistory. If it bothers someone, then it's their problem. I'm not afraid."[12] For this incident, Šimunić was fined 25,000kunas (around €3,270) by theState's Attorney Office of Croatia forinciting racial hatred and harassment of other participants of a public gathering.[13][14] After an investigation FIFA suspended Šimunić for ten official matches, banned him from entering the confines of the stadiums for those ten matches and imposed a fine ofCHF 30,000 (around €24,000).[15] Šimunić's behaviour was denounced by theCroatian Minister of Science, Education and SportsŽeljko Jovanović, the Association of Anti-Fascist Fighters of Croatia (SABH) and various foreign and domestic media.[13] The severity of suspension by FIFA was both criticized and embraced. Jovanović called it expected and deserving, sending a strong message that Croatians do not want to be perceived by Europe as "backward rightists" and as a country whereminority rights are being violated to promote and glorify fascism.[16] Others, such as theCroatian Football Federation and national team coachNiko Kovač, have described the suspension as excessive and draconian.[17] Šimunić appealed to rescind his suspension, but lost his appeal with FIFA in March 2014,[18] and with theCourt of Arbitration for Sport in May 2014.[19][20]
In 2019, Šimunić stated onSportske novosti: "I wasn't aware of the implications because I hadn't lived in Croatia for a long period of time and I hadn't felt such a division about certain questions, even if they were 'Za dom spremni'. So, to be very clear, I was not glorifying fascism,Nazism, or any other kind oftotalitarianism. I was glorifying Croatia. I was convinced that was the right way. Today I understand there is a lot of those who think that is the wrong way." and "Being aware of the context and everything that had happened, today I would chant 'Croatia, Croatia'".[21]
On 22 September 2015, Šimunić was appointed an assistant manager of theCroatia national team under the coaching staff ofAnte Čačić, who was sacked in October 2017.[22]
Šimunić is married to Christina Koloper, a Croatian Canadian. On 5 September 2014, Koloper gave birth to the couple's first child.[23] The child died in 2018.[24]