Damjanović signed a contract with FC Seoul on 7 December 2007.

He was the second highest scorer in the K-League in 2007, 2008 and 2009.
With 23 goals for Seoul in 2011 season, he was crowned the league's top scorer.

In July 2009, he managed to score two goals against Manchester United in United's Asian tour.
However, FC Seoul lost 3–2, United's goals being scored by Wayne Rooney, Federico Macheda and Dimitar Berbatov.

In January 2012, Chinese Super League club Guangzhou R&F offered $5 million to FC Seoul for Damjanović, but it was rejected by Seoul.
Damjanović scored his 100th career goal with FC Seoul from a penalty goal, along with the 101st in the same match over a 3–1 win against his former club Incheon United on 28 May 2012.
On 25 July 2012, he became top scorer in K-League foreign player history by scoring his 105th goal in the match against Daejeon Citizen.
The previous record holder is Saša Drakulić who made 104 goals in K-League.

In the first match of the 2012 K-League season, Damjanović was substituted out after 22 minutes against Daegu FC.
It had been speculated that the FC Seoul manager, Choi Yong-Soo, and Damjanović had a rift.
Damjanović wanted to leave but FC Seoul would not let him.
However, as time went on, FC Seoul issued an official statement by Choi saying there was no tension between the two.

He finished the 2012 K-League season with many accolades and records broken.
He scored 31 goals in 40 appearances, thus breaking the record held by Kim Do-Hoon in 2002.
He won the league with FC Seoul as well as becoming the Golden Boot winner, a spot in the K-League Best XI in the forward position, and the K-league MVP.

In January 2013, IFFHS ranked Damjanović seventh in the world for most goals in a top-division league surpassing players such as Zlatan Ibrahimović, Robin van Persie, and Wayne Rooney.

In September 2013, Damjanović scored in both of two legs of the AFC Champions League quarter finals against his former team Al-Ahli.
His scoring continued against the first leg of the semi-final against Esteghlal.

Despite scoring in both legs of the 2013 AFC Champions League Final against Guangzhou Evergrande, FC Seoul lost on away goals and thus ending the competition as runners-up.
Damjanović signed a contract with FC Seoul on 7 December 2007.
He was the second highest scorer in the K-League in 2007, 2008 and 2009. With 23 goals for Seoul in 2011 season, he was crowned the league's top scorer.
In July 2009, he managed to score two goals against Manchester United in United's Asian tour. However, FC Seoul lost 3–2, United's goals being scored by Wayne Rooney, Federico Macheda and Dimitar Berbatov.
In January 2012, Chinese Super League club Guangzhou R&F offered $5 million to FC Seoul for Damjanović, but it was rejected by Seoul. Damjanović scored his 100th career goal with FC Seoul from a penalty goal, along with the 101st in the same match over a 3–1 win against his former club Incheon United on 28 May 2012. On 25 July 2012, he became top scorer in K-League foreign player history by scoring his 105th goal in the match against Daejeon Citizen. The previous record holder is Saša Drakulić who made 104 goals in K-League.
In the first match of the 2012 K-League season, Damjanović was substituted out after 22 minutes against Daegu FC. It had been speculated that the FC Seoul manager, Choi Yong-Soo, and Damjanović had a rift. Damjanović wanted to leave but FC Seoul would not let him. However, as time went on, FC Seoul issued an official statement by Choi saying there was no tension between the two.
He finished the 2012 K-League season with many accolades and records broken. He scored 31 goals in 40 appearances, thus breaking the record held by Kim Do-Hoon in 2002. He won the league with FC Seoul as well as becoming the Golden Boot winner, a spot in the K-League Best XI in the forward position, and the K-league MVP.
In January 2013, IFFHS ranked Damjanović seventh in the world for most goals in a top-division league surpassing players such as Zlatan Ibrahimović, Robin van Persie, and Wayne Rooney.
In September 2013, Damjanović scored in both of two legs of the AFC Champions League quarter finals against his former team Al-Ahli. His scoring continued against the first leg of the semi-final against Esteghlal.
Despite scoring in both legs of the 2013 AFC Champions League Final against Guangzhou Evergrande, FC Seoul lost on away goals and thus ending the competition as runners-up.
Dejan Damjanović