Joining the army in his teens, Joyce served as a private in the Black Watch before attending University and subsequently receiving a commission in the Royal Army Educational Corps. He resigned from the army under threat of discharge in 1999 at the rank of Major after being found to have broken Queen's Regulations. He then worked as the Public Affairs Officer at the Commission for Racial Equality (Scotland).
From 2003, Joyce served as a Parliamentary Private Secretary (PPS) to several UK government ministers. He resigned as the PPS to Bob Ainsworth on 3 September 2009, citing concerns over the war in Afghanistan.
Joyce was arrested five times during his last five years as an MP, most notably in February 2012 on suspicion of assault after an incident in the Houses of Parliament. This led to his immediate suspension from the Labour Party, before pleading guilty to all charges and resigning from the party the following month. He continued representing his constituency as an independent for the remainder of the parliamentary term.
Joyce lived in Perth, Scotland, with his family for most of his childhood and adolescence. He joined the Army in 1978, initially as a private in the Black Watch before taking a sabbatical between 1981 and 1987 to attend technical college and university where he gained a BA (Hons) in religious studies from Stirling University. As a university candidate, he was made a probationary second lieutenant on 25 August 1987.
In 1987 he attended the Royal Military Academy Sandhurst before being commissioned into the Royal Army Educational Corps (later Adjutant General's Corps) as a subaltern with seniority to 7 October 1981. After receiving his commission he continued his studies part-time and acquired an MA in Education from the University of Bath and an MBA from Keele University. During his time in the army he served in Great Britain, Northern Ireland, Germany and Central America. He was promoted to captain on 25 January 1990 and to major in 1992.
Joyce publicly described the armed forces as "racist, sexist and discriminatory", A Fabian pamphlet by Joyce titled Arms and the Man: renewing the armed services had been published without the proper authorisation, breaching Queen's Regulations which govern the conduct of officers in the British armed forces, He continued to speak out about how he perceived the army to the disapproval of his superiors. At a hearing in January 1999 which invoked the Pay warrant rules, Joyce was requested to resign from the army by 13 March or be discharged. He resigned his commission on 12 March 1999 and left the army,
Joyce subsequently served on the staff of the Commission for Racial Equality (Scotland) before his election to the House of Commons.
He was first elected to parliament at the 2000 Falkirk West by-election, which was prompted by the resignation of Dennis Canavan. On election he served as a member of the Scottish Affairs and the Procedures Select Committees at Westminster. Joyce retained his seat in the 2001 general election, and was elected to the enlarged Falkirk constituency in the 2005 general election.
From 2003 Joyce served as a Parliamentary Private Secretary (PPS) to a number of British Government ministers. He resigned as the Parliamentary Aide to Bob Ainsworth on 3 September 2009 citing concerns over the war in Afghanistan. He had previously been PPS to John Hutton during three of Hutton's cabinet posts: when he was the Secretary of State for Defence; Secretary of State for Business, Enterprise and Regulatory Reform and Secretary of State for Work and Pensions. Prior to that, Joyce served as the parliamentary aide to ministers Mike O'Brien MP, when O'Brien was the Minister for Energy at the Department of Trade and Industry and Margaret Hodge MP, Minister for Industry and the Regions at the Department of Trade and Industry.
Joyce persuaded the Treasury to change the child benefit regulations to remove a discrepancy that disadvantaged young Scottish FE students relative to their peers in the rest of the UK. In April 2008, Joyce became the first European parliamentarian to be granted an opportunity to address the newly formed Parliament of the Democratic Republic of the Congo, when he visited the DRC as the chair of the all-party parliamentary group on the Great Lakes Region of Africa with other members of the group. In September 2008, Joyce was criticised by local government councillors for describing the name of the new Clackmannanshire Bridge as "unimaginative" and "parochial". The naming of the bridge was reported as a contentious matter.
Joyce edited Now's the Hour!: new thinking for Holyrood and has served as Chair of the National Executive of the Fabian Society.
In September 2011 he contributed to the book What next for Labour? Ideas for a new Generation; his piece was entitled "It's a Sin".
Joyce most often put questions in the House of Commons to the Scotland Office, Department for International Development, Foreign and Commonwealth Office, Northern Ireland Office, and Ministry of Defence. While a Parliamentary Private Secretary Joyce was expected to vote with the Government, but even when not, he has not broken the Labour whip in Parliament. Joyce was not a member of any Parliamentary Select Committees at the end of his time in the Commons, but has been a member of several public bill committees.
Joyce, along with fellow former MPs Tom Harris and Jo Swinson, regularly used the social networking tool Twitter during Parliamentary business including during Prime Minister's Questions to encourage constituents to feel involved with parliamentary proceedings. The activities are permitted under parliamentary rules.
Joyce was the top-claiming Member of the House of Commons for the 2005–06 Parliamentary session, claiming £174,811 in expenses, of which 62% was for staff and office costs. After the 2005–06 Parliamentary session he made a public pledge to cut his expenses; during the 2006–07 session he moved down to 11th on the list of MPs' expenses and allowances, but again rose to the top for 2007–08 with £187,334.
In October 2007 he claimed £180 for three oil paintings. When asked why he had used taxpayers' funds in such a way he replied "because they look nice."
In 2012 Joyce waged an internet campaign against the Scots Gaelic language. Using his Twitter account, he derided the language as being "an old, unadaptive language with relatively few words for things" and Gaelic poetry as "basically doggerel" and "mainly a bit of rubbish". He was criticised for his views by the Scottish Government.
On 18 November 2010, he was arrested for failing to provide a breath test following a motoring incident in Falkirk. He pleaded guilty in court the following day and was fined £400 and banned from driving for a year. Joyce resigned from his position as Shadow Northern Ireland Minister and apologised for his behaviour.
Joyce was arrested at 22:50 on 22 February 2012 in the Palace of Westminster by the Metropolitan Police on suspicion of committing assault. He was reported to have attacked as many as six politicians, including a Labour whip, after having gone "berserk" following a dispute with a group of Tory MPs sitting nearby. He headbutted and punched the Conservative MP, Stuart Andrew, after striking Labour Assistant Whip, Phil Wilson, while Wilson was attempting to restrain him. He also headbutted Thurrock Conservative Councillor, Ben Maney, and punched Basildon Conservative Councillor, Luke Mackenzie, both of whom were attempting to break up the incident. Two more Conservative MPs, Alec Shelbrooke and Jackie Doyle-Price, were also caught up in the fracas while attempting to intervene and calm Joyce down. A door window was smashed as Joyce attempted to resist arrest before being removed by police and taken to Belgravia police station. The disturbance occurred at the Strangers' Bar (reserved for MPs and their guests).
Suspended the following day from the Labour party after his arrest, on 23 February he was charged with three counts of common assault and released on police bail. A fourth charge was added on 9 March. He was fined £3,000 and ordered to pay £1,400 in compensation to his victims, but not given a custodial sentence. In a statement before the House of Commons on 12 March 2012, he apologised personally to his victims, stated that he had resigned from the Labour Party, and that he intended to complete his current term as an MP but not seek re-election.
In August 2012, Joyce was back in Court after using scissors on 4 July 2012 to remove the electronic tag that had been fitted to his leg as part of the community order; he was fined £600.
A year later, on 14 March 2013, Joyce was again arrested after a disturbance during a karaoke event in the sports and social bar of the House of Commons. He was seen outside the bar wrestling on the floor with two police officers and reportedly had one of the officers in a headlock. As it was his second alcohol-related incident on House of Commons premises, the following day Joyce was given an indefinite ban by the Office of the Speaker from purchasing or being served alcoholic beverages from all Palace of Westminster premises, including its eight bars.
Joyce was released under police bail from Belgravia Police Station in London the following day, when it was revealed that he was facing a charge of occasioning actual bodily harm, but he was not ultimately prosecuted.
On 19 May 2013, Joyce was arrested at Edinburgh Airport after police were called to an altercation between himself and airline staff regarding a mislaid mobile phone. He was reported to have struggled with police officers before being restrained on the ground and handcuffed. On 21 March 2014, he pleaded guilty to a charge of breach of the peace at Edinburgh Sheriff Court and was fined £1,500 with £150 compensation.
On 17 October 2014, Joyce was arrested after 'clashing' with a teenager at a store in Camden (later described as being in Chalk Farm), in London. He was charged with two counts of common assault and one count of criminal damage. He appeared at Highbury Corner Magistrates' Court in London on 30 December 2014, where he pleaded not guilty and was given conditional bail to appear for trial. On 1 May 2015, he was found guilty on two counts of common assault in an appearance at Westminster Magistrates' Court in London. On 27 May 2015 he was sentenced to a 10-week jail term suspended for two years, and ordered to pay a £1,080 fine and to attend a rehabilitation course which aims to reduce violent behaviour.