He was born in Rutherglen, Scotland on 7 September 1987. 

Trainee at Livingston

He joined Livingston as a trainee in July 2003 and progressed to their first team. Before becoming a professional with them he declined a transfer to Blackburn Rovers. On 31 January 2007 they loaned him to Stirling Albion until the end of the season. He played in 15 League and Cup matches for Stirling, scoring 7 goals.

In 2007 and 2008 he played 3 times for Scotland Under20 and in 2 matches for Scotland Under21. He did not score in any of those matches.

He declined the offer of a new contract with Livingston at the end of 2007/08. He had played in 92 League and Cup matches for them, scoring 17 goals. He had a trial with Barnsley but was not taken on. 

Leeds United

On 25 July 2008 he was transferred from Livingston to Leeds United. He played in 191 League and Cup matches for them, scoring 41 goals. While with Leeds United he played 5 times for Scotland, scoring once, with his first appearance in the 3-0 victory away to Northern Ireland on 9 February 2011. 

6’ 0”;   12st 2lb;   A midfield player.  

Transferred to Norwich City

He declined the offer of a new contract with Leeds United and on 26 July 2012 he was transferred to Norwich City for an undisclosed fee (reported as £3.2 million).

He played in 74 first team matches for City, scoring 14 goals.  

While with City he played in 10 matches for Scotland: scoring 2 goals. 

In May 2014 he was voted Norwich City Supporters Player of the season and was presented with the Barry Butler Memorial Trophy.

Move to Hull City

On 30 June 2014 Norwich City announced that he had been transferred to Hull City for an undisclosed fee (reported as “about £7 million, possibly increasing to £8 million if certain conditions were fulfilled”; the most City had received for a player). He joined them on a 3 year contract. In his first Premier League match for them he sustained a dislocated kneecap and was unable to play for several months. He played for Hull City in 56 League and Cup matches, scoring 13 goals. 

On 27 January 2017 Hull City transferred him to West Ham United for a reported fee of £10.2 million. On 25 August 2017 Aston Villa announced that he had joined them on loan from West Ham until the end of the season. He played in 43 League and Cup matches for Villa, scoring 7 goals, and was in their team for the 1-0 defeat by Fulham in the English Football League, Sky Bet Championship playoff Final at Wembley Stadium on 26 May 2018.

In 2019 he announced his retirement from international football. He had played 29 times for Scotland, starting 21 of those matches and scoring 7 goals. The last of those international matches was on 10 October 2019.

On 8 January 2021 West Ham United (where he had played in 86 League and Cup matches for them, scoring 11 goals) announced that he had been transferred to West Bromwich Albion for an undisclosed fee. 

On 31 January 2022 West Bromwich Albion announced that he had left them by mutual agreement. He had played for them in 15 League and Cup matches, without scoring. On 25 February 2022 Luton Town announced that he had joined them on a contract to the end of the season. He played for them in 11 League and Cup matches, without scoring.

Retirement

On 6 September 2022 Heart of Midlothian announced that he had joined them. They announced in April 2023 that he was being released. He did not play subsequently for another club and in January 2024 he announced his retirement as a professional player.