Spoken about as a talented footballer at a young age, Muntari started his youth career in Ghana with Liberty Professionals before joining Udinese where he progressed from their academy into becoming a first team player.

He became a regular member of Ghana under-20 team at the age of 16 as they finished runners-up at the 2001 FIFA World Youth Championship in Argentina, losing out to the hosts in the final.

He eventually opted for Portsmouth[11] and transferred on 30 May 2007, for a new club record fee, believed to be around £7.1 million, signing a five-year contract.

Injuries to Esteban Cambiasso and Patrick Vieira underlined just how short of ball-winning midfielders the Nerazzurri were, and they would be looking to remedy the problem in June 2007.

[36][37] He finally completed his move to Inter on 28 July 2008 and wore the number 20 jersey,[38] previously worn by Álvaro Recoba for many years.

On 24 August, Muntari made his competitive debut for Inter Milan in the club's victory over Roma in the Italian Super Cup.

On 22 November 2008, Muntari scored the winner, redirecting a wayward Zlatan Ibrahimović shot, in the Derby d'Italia against rivals Juventus.

Two weeks later, Muntari scored a backheel goal against Napoli at the San Siro after a great cross from Maicon, a match that ended 2–1 for Inter.

In the very last Serie A match of the season, on 31 May 2009 against Atalanta, he opened the scoring for Inter after blasting in a Luís Figo cross from outside the penalty box.

[47] The following match day, Muntari played the full 90 minutes and scored his second goal of the season after a shot from Moussa Marega deflected off him, to help Inter Milan to a 3–1 win over Atalanta.

He played in all of Inter Milan's Coppa Italia matches that season, as the club won the competition for the sixth time in its history.

[50] During Inter Milan's first Champions League match of the season, Muntari started and played 62 minutes before taken off for Dejan Stanković in their goalless draw against Barcelona.

[53][54] In the final, Muntari came on as a second-half substitute, after Diego Milito had secured the title with two goals against Bayern Munich at the Santiago Bernabeu.

[52]After José Mourinho's departure, in the 2010–11 season, Muntari fell down the pecking order and was considered a fringe player by new manager Rafael Benitez.

There were multiple reports most notably from Sky Sports that Muntari wanted to leave for another team where he would be a first-team regular after missing out on the match-day squad for their match against Juventus on 5 October.

[61][62] On 15 January 2011, Inter Technical Director Marco Branca confirmed Muntari had handed in an official transfer request.

On 20 February 2013, Muntari scored a goal to give Milan a two-goal lead against Barcelona ahead of the second leg in the last 16 tie in the UEFA Champions League.

[73] Later that month, he was fined €10,000 and suspended for two matches after being sent off during a game against Roma for manhandling referee Gianluca Rocchi whilst protesting a call.

[81][82] He made his league debut for the Jeddah-based club on 20 August, in their first match of the season, playing the full 90 minutes as they defeated Najran SC 2–1.

[86] The following month, in their second leg against Lokomotiv Tashkent, he scored his third goal for the club, a long range effort which helped Ittihad to another 1–1 draw.

[99] Due to his lack of fitness, Muntari did not make a mach day squad for Albacete until 2 March 2019, when he was named on the bench and was unused substitute in their 1–0 loss to Cádiz CF.

[102] On 7 April 2019, he started his match for the club, assisting Aleix Febas to score the game-winning goal against AD Alcorcón to grant them a 1–0 away win.

[103][104][105] After two-years without a contract, Muntari returned to active football and joined Ghana Premier League giants Hearts of Oak on a six-month deal.

[109] On 6 February 2022, he made his debut as a substitute in a 1–0 loss to rivals Accra Great Olympics, coming on in the 79th minute for William Dankyi.

[110] The following match day, he made his first start for the club in their goalless draw against Real Tamale United at the Aliu Mahama Stadium.

He won his first senior cap against Slovenia on 17 May 2002, and became a regular fixture in the team as The Black Stars opened their 2006 FIFA World Cup qualifying campaign.

[123] This started a dispute between Muntari and the Ghana Football Association (GFA), and he said that he would refuse to play for his country again, setting the "record" for the youngest international retirement.

[130] However, after an intervention by former captain Stephen Appiah, he was reinstated[131] and went on to make two further substitute appearances against Germany and the United States before starting the quarter-final against Uruguay in place of the suspended André Ayew.

[134] Muntari and Kevin-Prince Boateng were sent home from the Black Stars camp in Brazil and suspended from the Ghana squad on 26 June 2014 for disciplinary reasons, only hours before the final Group match against Portugal.

[135][136] A former left-back,[137] Muntari later developed into a powerful, experienced, hard-working, and tenacious midfielder; although he is primarily known for his physical strength and combative playing style, he was also able to make notable improvements to his technical skills throughout his career.