Early career Koren played for
Dravograd and
Celje in his home country, before transferring to Norwegian side
Lillestrøm in 2004.
West Bromwich Albion On 4 January 2007, Koren signed for English
Championship club
West Bromwich Albion in a
Bosman ruling, penning an 18-month contract with a further year's option in the club's favour. He made his debut two days later as a late substitute in the Baggies' 3–1 win over
Leeds United in the
FA Cup third round. Koren scored his first goal for the club in a 7–0 home win against
Barnsley on 6 May 2007, the last day of the league season. The victory ensured Albion's place in the Championship promotion play-offs. Koren started all three play-off games as Albion beat
Wolves in the two-legged semi-final but lost 1–0 to
Derby County in the
Wembley final. In July 2007 Koren suffered a freak accident in training when a ball hit him in the eye, causing internal bleeding and temporary loss of vision. Although he made a full recovery, he later admitted that he had feared for his sight. The injury meant that he missed the start of the
2007–08 season, but he returned to the side at the end of August as a substitute in a
League Cup game against
Peterborough. In mid-September he signed a new two-year contract at Albion, with a further year's option in the club's favour. He has been described by former West Brom manager
Tony Mowbray as a "model pro". Koren's two goals in Albion's 3–2 defeat away at
Southampton in October 2007 earned him a place in the
Championship Team of the Week. Koren scored his first Premier League goal on 17 January 2009 and was named man of the match as Albion beat
Middlesbrough 3–0. His goal in Albion's 2–2 draw with Burnley in the FA Cup earned him the
ITV goal of the round. In the 2008–09 Premier League season, Koren proved his reliability and consistency by making the most appearances of the season for an outfield player at West Brom, only appearing fewer times than goalkeeper
Scott Carson. Koren continued to be a regular starter during the 2009–10 season under new manager
Roberto Di Matteo, making 34 league appearances and scoring 5 goals, including a brace in a 3–0 home win against
Leicester City in April as West Brom sealed an immediate return to the top flight. Despite a strong end to the season, on 17 May 2010, Koren was released by West Brom after the club chose not to take up their option to extend his contract.
Hull City in 2012 On 13 August 2010, Koren joined
Hull City on a free transfer, signing a two-year contract with an option of a third year. He made his debut for the club when he came on as a replacement for
Will Atkinson at
Millwall on 14 August 2010. He scored his first goal for the club in a 2–0 home victory over
Derby County on 14 September 2010. He also scored goals away at
Norwich City and
Leicester City, including a 25-yard strike at home against
Ipswich Town, and also scored what proved to be the winning goal in a 2–1 away victory over
Watford. On 24 September 2011, against
Bristol City at
Ashton Gate Stadium, Koren played a neat ball into
Aaron McLean's feet and when the pass was returned, Koren stroked a lovely low shot into the bottom corner of the net. On 22 October 2011 against Watford at the KC Stadium, Koren picked up possession midway inside the City half, drifted past three Watford players before driving home into the bottom corner of the net from 25 yards. On 29 November 2011, against
Southampton at
St Mary's Stadium, a flowing move down the left ended with
Tom Cairney pulling the ball back to Koren, whose shot deflected off
Matty Fryatt and brought a stunning save out of
Kelvin Davis. But the rebound fell for Koren, who nodded home from close range. On 3 December 2011, against Leicester City at the KC Stadium, the ball was rolled nicely into the path of Koren and he struck a beautiful shot past
Schmeichel from 20 yards. On 7 December 2011, against
Birmingham City at the KC Stadium,
Cameron Stewart got to the byeline down the right before firing in a vicious cross that was only cleared as far as the penalty spot where Koren readjusted his body to volley into the net. On 15 September 2012, against Millwall at the KC Stadium, Koren picked up possession on the edge of the centre circle, advanced unchallenged before unleashing a powerful drive from 25 yards which flew past
Taylor and into the net. After Hull's promotion to Premier League he was ruled out for four to five weeks for foot injury before the clash against
Newcastle United.
Melbourne City On 3 August 2014, Robert Koren was announced as a marquee signing for
Melbourne City in the
A-League. After missing the first 10 games of the season with injury, on 20 December 2014 Koren made his debut in the
Melbourne Derby, coming on as a substitute. On 30 December 2014, Koren scored a hat trick against
Newcastle Jets in his first starting game. On 21 January 2016, he was released from his contract to pursue new opportunities. ==International career==