Reim played most of his professional career in Estonia as a central midfielder, including two separate stints for Flora with which he won seven Meistriliiga titles.

[7] Reim made his international debut for Estonia on 3 June 1992, in a historic 1–1 draw against Slovenia in a friendly at Kadriorg Stadium.

[2] On 2 June 2001, Reim made his 100th appearance for Estonia in a 2–4 home loss to the Netherlands in a qualification match for the 2002 FIFA World Cup.

Flora successfully defended their title in 2011 season and won the 2010–11 Estonian Cup, defeating Narva Trans 2–0 in the final.

On 14 October 2012, Reim resigned after poor results in the Meistriliiga, with Marko Lelov and Norbert Hurt taking over.

On 14 September 2016, the Estonian Football Association appointed Reim as manager of the Estonia national team until the end of the qualification tournament for the 2018 FIFA World Cup.

[12] On 17 June 2019, he and his coaching staff resigned from Estonia national team, six days after the 0–8 defeat to Germany in the UEFA Euro 2020 qualification.