He was selected sixth overall in the 2001 NHL Entry Draft by the Minnesota Wild and continued to play with TPS for three more seasons.

[11] During the ensuing off-season, he signed a then-franchise-record seven-year, $47 million contract extension on 16 July 2010, which went into effect during the 2011–12 season.

[15] On 28 February 2016, Koivu surpassed Nick Schultz's 743 games played with the Minnesota Wild to own this franchise record as well.

[17] On 6 February 2019, Koivu was ruled out for the remainder of the 2018–19 season after suffering a tear in his Anterior cruciate ligament (ACL) and meniscus in his right knee.

[19][20] On 10 October 2020, Koivu ended his 15-year tenure with the Wild and signed as a free agent to a one-year, $1.5 million contract with the Columbus Blue Jackets.

Koivu did double duty in 2001, also participating in the World Junior Championships, earning a silver medal while contributing three assists.

He played in his second World Junior Championship the following year in 2002, tallying five points in six games as Finland captured another silver medal.

These junior years also marked the start for Koivu's long-time collaboration in the national team with Tuomo Ruutu, with whom he has been often paired as an effective playmaker-scorer duo ever since, in similar manner as his older brother Saku usually found himself with Teemu Selänne.

Before making his North American debut in the AHL, Koivu competed in the 2004 World Cup as Finland finished runner-up to Canada.

In the 2008 World Championships, Koivu became a key contributor, tallying an international career-high nine points in nine games as Finland won the bronze medal.

Koivu was part of the team that won the bronze medal at the 2010 Winter Olympics in Vancouver, British Columbia, Canada.

Koivu was also selected to represent Finland at the 2014 Winter Olympics in Sochi, but was forced to withdraw from the squad due to an injury sustained in the NHL.

[32] Note: In March and April 2009, and then for the start of October 2009, Mikko Koivu was captain as part of the Minnesota Wild's rotating captaincy.