Born and raised in England, Bruce has played twice for the Northern Ireland national team, for which he declared himself available in 2011 and made his debut in 2013. He had previously made two appearances for the Republic of Ireland in 2007–08, but was allowed to switch under FIFA eligibility rules as these had been in friendly matches.
Bruce was born in Norwich, Norfolk, but moved to the Greater Manchester area at the age of three when his father, centre-back Steve Bruce, was transferred from Norwich City to Manchester United. He joined the Manchester United Academy, but was released at age 16 and moved to Blackburn Rovers as a trainee. He signed his first professional contract there in 2002, and was part of their under-19 team that won the FA Premier Academy League in 2002–03. He made his first-team debut on 26 December 2004 against Hartlepool United, while on three months' loan to League One club Oldham Athletic, and was part of the Oldham team that beat Manchester City in the FA Cup on 8 January 2005. He signed on a free transfer for Birmingham City, where his father was manager, on 27 January 2005.
After finishing his loan spell at Oldham and returning to his parent club, he joined Sheffield Wednesday again on loan until the season's end, and contributed to their promotion via the play-offs. Bruce's performances against Tranmere Rovers impressed that club's manager, Brian Little, who signed him on loan for the first half of the 2005–06 season, but the loan was terminated early by mutual consent.
Bruce made a few Premier League appearances for Birmingham following his return, including coming on as a substitute against Liverpool when Birmingham were getting heavily beaten. The team were relegated to the Championship, and it was felt that accusations of nepotism were hindering his progress, so it was decided that, in the best interests of club, manager and player, Bruce should pursue his career away from his father's management.
In the summer of 2006, he moved to Ipswich Town on a free transfer, signing a three-year contract. In early summer 2007 he was called up as an international player by the Republic of Ireland, and in November 2008, he was reportedly being watched by Italian club Fiorentina, having been recommended by Ireland manager Giovanni Trappatoni. Bruce scored his first goal for Ipswich, away to his former club Birmingham City, on 24 October 2008. He ended speculation he would leave the club by signing a new two-year contract in May 2009. Bruce captained the side at the start of the 2009–10 season, initially because Gareth McAuley was absent through injury and loss of form, but manager Roy Keane confirmed in late August that Bruce would keep the captaincy even if McAuley returned to the team. He fell out of favour with Keane, and lost his place in the starting 11.
On 1 February 2010, Bruce joined Leicester City on loan for the rest of the season; he jumped at the opportunity "for a change and a new challenge." He made his debut as a substitute during injury time in a 2–1 win over Blackpool at Bloomfield Road on 7 February, playing for less than a minute. Half an hour into his full debut, he suffered a hernia that required surgery, and kept him out for several weeks. He recovered in time to play in the last three matches of the season, partnering Jack Hobbs in central defence as Leicester lost the Championship play-off semi-final to Cardiff City on penalties.
In July 2010, a transfer to Sheffield United was discussed but not completed; press speculation suggested the clubs had failed to agree on how the £200,000 fee should be paid. On 30 July, Bruce joined Championship club Leeds United for an undisclosed fee. He signed a two-year deal with an option for a further year. Bruce was an unused substitute in Leeds' first game of the season, and made his debut in the League Cup against Lincoln City on 10 August, coming into the starting 11 in place of captain Richard Naylor; Naylor took his place back for the next League match. Bruce made his second start in the next round of the League Cup, against his former club Leicester City.
In his first League appearance, again replacing the rested Naylor, this time against Doncaster Rovers on 17 September, Bruce helped Leeds keep a clean sheet. He kept his place for the next game, against Sheffield United, and scored his first Leeds goal in the next, a 6–4 home defeat against Preston North End. After Naylor came back into the side, Bruce moved to right back against his former club Ipswich Town, and was sent off after receiving a second yellow card for a foul on Andros Townsend. After a spell on the bench, Bruce returned to Leeds' starting line-up against Cardiff City. After cementing his place in the side in partnership with Andy O'Brien, Bruce picked up an injury against Queens Park Rangers and had to be substituted early in the first half. In January 2011, Bruce was part of the Leeds team that came close to eliminating Premier League Arsenal from the FA Cup. Leeds took the lead through a Robert Snodgrass penalty, but Cesc Fàbregas equalised in the 90th minute, also via a penalty. After Leeds conceded eight goals in the last three games in February, Leigh Bromby replaced Bruce in the defence, and Bruce made no further appearances that season.
The return to fitness of Patrick Kisnorbo provided additional competition in defence. Bruce scored in a pre-season victory against Motherwell, and played in a reserve-team friendly against non-league club Farsley Celtic, but missed the first few months of the season through injury, including damage to an ankle.
On 24 November, he joined League One club Huddersfield Town on loan until 2 January 2012. He made his debut in Town's 1–0 home defeat to AFC Bournemouth on 10 December, and played twice more before Leeds invoked a 24-hour recall clause after an injury to Tom Lees. He returned to Leeds' starting lineup for the first time in nearly a year for the 2–1 win against Burnley on 2 January, but that was his only appearance in January, and he was linked with a move to Los Angeles Galaxy. No move took place, and Bruce made seven more appearances before being released by manager Neil Warnock when his contract expired at the end of the season.
Bruce signed a two-year deal with Championship club Hull City, where his father was manager, on 30 July 2012. He played 32 games and became an integral part of the team that earned promotion to the Premier League as Championship runners-up during the 2012–13 season. In his second season at the club, Bruce played 20 Premier League matches.
On 17 May 2014 he started the 2014 FA Cup Final against Arsenal, but was on the losing side after Aaron Ramsey scored in extra time to give Arsenal a 3–2 victory.
On 20 October 2015 he scored his first goal for Hull City with a 36th-minute header, after coming on for the injured Curtis Davies in the 18th minute of a 3–0 win against his former club, Ipswich Town.
On 31 January 2017, he moved on loan to Wigan Athletic until the end of the season.
In August 2017, Bruce joined League One club Bury on non-contract terms. Just 15 minutes into his debut, on 13 August away to Wigan Athletic, he scored with a header to tie the scores at 1–1; he played 75 minutes, and his team lost 4–1. Bruce left Bury on 30 August 2017 by mutual consent.
The following day, he rejoined Wigan Athletic until the end of the season.
Qualifying through his paternal grandmother from Bangor, Northern Ireland, Bruce was eligible for international football for both Northern Ireland and the Republic of Ireland in addition to England, where he was born and brought up. He was called up by the Northern Ireland under-21s, but opted to play for the Republic instead, and made his debut for their under-21 team against Sweden in February 2006. He also represented Republic of Ireland B against Scotland B in November 2006.
On 23 May 2007 he made his full international debut in a friendly match for the Republic of Ireland against Ecuador played at Giants Stadium, New Jersey. He captained the Republic of Ireland B team which played Nottingham Forest in a challenge match at Dalymount Park on 9 October 2008.
In July 2011, Bruce switched his international allegiance to Northern Ireland. This was possible under FIFA eligibility rules because Bruce's appearances for the Republic had been in friendly matches. He was first called into the Northern Ireland squad in October 2012, for the World Cup qualifier against Portugal, but injury forced his withdrawal. He made his Northern Ireland debut against Malta in a friendly on 6 February 2013.
When Bruce joined Leeds United, he was reunited with his childhood friend, the Leeds goalkeeper Kasper Schmeichel; their fathers, Steve Bruce and Peter Schmeichel, had played together in the same positions at Manchester United.
In December 2010, Bruce was involved in a car crash during a snow storm, but managed to escape from the crash unharmed.
Bruce married his partner Lucy in 2015.As of match played 19 August 2017
As of match played 5 March 2014
Sheffield WednesdayFootball League One play-off winner: 2004–05
Hull CityChampionship runner-up: 2012–13
FA Cup runner-up: 2013–14