During his career, Mellberg played as a defender, and is best known for his time at Aston Villa, as well as spells with Juventus and Greek side Olympiacos.

After being relegated, he joined capital club AIK, where he made an instant impression, became Swedish champion 1998 and was sold after just ten months.

[4] Mellberg was left out of boss David O'Leary's first side for a game against Portsmouth, but was soon made the captain of the English giants for the rest of his reign.

In 2007 the new manager of Aston Villa, Martin O'Neill, continued to consider Mellberg as the first choice centre back.

On the opening day of the 2006–07 Premiership season Mellberg became the first person to score in a competitive game at Arsenal's new Emirates Stadium.

In January 2008, it was confirmed that Mellberg had signed a pre-contract agreement with Italian giants Juventus, allowing him a Bosman move to Serie A on a three-year contract for the start of the 2008–09 season.

Mellberg turned down a new deal at the end of the 2011–12 season to extend his time in Athens, hoping to find a new challenge with his agent saying, "...we don't close any doors.

Since then, the two of them have been known for not being the best of friends, and in the 2006 World Cup, Mellberg and Ljungberg, according to leak from inside the team, had a very fiery argument, after Sweden's draw with Trinidad and Tobago.

[16] During a 2006 FIFA World Cup Qualifying match against Croatia in October 2005, Mellberg boxed the ball away with his hand in the Swedish penalty area.

After the 2006 FIFA World Cup in Germany, Mellberg relinquished his captaincy and Ljungberg took his place as Sweden captain.

[17] On 4 September 2006, Mellberg, along with Sweden teammates Zlatan Ibrahimović and Christian Wilhelmsson, was sent home from the national squad for breaking an 11 pm team curfew ahead of a European Championships qualifier against Liechtenstein.

[29] Following the resignation of Janne Andersson from the role as manager, Mellberg was one of the many candidates for head coach the Swedish Football Association pursued.

Others considered for the role included Graham Potter,[30] IF Elfsborg manager Jimmy Thelin and Henrik Larsson.

[31] On 26 November 2024, Mellberg was announced as the new head coach of Major League Soccer club St. Louis City.