Sens Sagna started his career at
FC Sens. He played for their youth team until 1998.
Auxerre In 1998, he moved to
AJ Auxerre's youth team. Eventually, he was promoted to the first team and he made 87
Ligue 1 appearances for them. He was part of the squad that won the
Coupe de France in
2005. He also played in the
UEFA Cup in each of his three seasons with the club's first team, making a total of 17 appearances in the competition. He was also voted into the Ligue 1 team of the season for his outstanding displays at the right back position. He played in the same Auxerre team as
Abou Diaby, a future
Arsenal teammate, and
Watford centre-back
Younès Kaboul. Sagna established himself as one of the best full backs of the French top tier and thus became dubbed "Mr. Reliable" by the club's fans. He also won Auxerre's Player of the Year award for the 2006–07 season. He was given the number 3 shirt, previously worn by former defender
Ashley Cole. Sagna made his debut for Arsenal on 19 July 2007 as a starter in the squad that beat Turkish club
Gençlerbirliği 3–0 in a friendly at Austria's
Bad Waltersdorf Stadion. On 13 February 2008, exactly one week before Arsenal were set to play the second leg of their round of 16 encounter against
Milan in the
Champions League, Sagna's older brother, Omar Sagna, died at the age of 28, one day before his birthday. He, however, did play the match after he was advised to by his father. Arsenal went on to win the second leg 0–2 with the same scoreline on aggregate. On 23 March, Sagna tallied his first
Premier League goal off a low header from a corner kick to give Arsenal a 1–0 lead against
London rivals
Chelsea at
Stamford Bridge, but later went off injured before Chelsea came back to win the game 2–1. At the end of the season, he was named in the
PFA Team of the Year.
2008–09 season Sagna signed a new deal with Arsenal before the start of the
2008–09 season. Arsenal signed him for a further two years, taking his contract up to 2014. Sagna stated, "I love Arsenal, it's a great club," and further added, "The manager is also very good and next season we will be fighting for all the trophies." He stunningly saved Arsenal in a 2–2 draw against
Aston Villa when he jumped and kicked the ball away so that Arsenal would go into half time with the lead.
2009–10 season Sagna struggled to replicate his form from the previous two seasons as injuries also prevented him from contributing to the team in the same way. He provided many assists though, his most important contribution arguably being the cross to striker
Nicklas Bendtner, who gave Arsenal the 1–0 lead in the 94th minute against
Wolverhampton Wanderers. Despite this, however, Sagna was linked away from the club with various teams, including
Serie A's
Internazionale, seemingly interested in taking the defender away from London.
2010–11 season Sagna scored his first goal at the
Emirates Stadium for Arsenal against
Celtic, a game in which Arsenal went on to win 3–2 and win the
Emirates Cup for the second consecutive year. He made his 100th league start for Arsenal on 3 October 2010, a 2–0 defeat against Chelsea at Stamford Bridge. On 14 November, he scored only his second ever official goal for Arsenal in a 2–1 away victory against
Everton at
Goodison Park, with a powerful shot from the near post. On 8 December 2010, Sagna picked up his first red card in his Arsenal career in a 3–1 home victory against Serbian club
Partizan in Arsenal's final
Champions League group game of the season. On 1 January 2011, in a match with
Birmingham City, he was involved in an incident where
Lee Bowyer stamped on him after Sagna had gone in for a tackle. Bowyer was banned by the
FA for three games for the stamp. On 5 January, Sagna picked up his second red card of the season after he and
Manchester City fullback
Pablo Zabaleta headbutted each other in the final moments of Arsenal's 0–0 draw with City at Emirates Stadium. On 19 January, Sagna scored his second goal of the season with Arsenal's second goal in their 3–1 victory over
Leeds United at
Elland Road in a third round replay. This was Sagna's career best for goal-scoring, his previous best coming in the 2007–08 season where scored only once. Sagna was included in the PFA Team of the Year for his performance in the
2010–11 season.
2011–12 season On 13 August 2011, Sagna started and played the full 90 minutes against
Newcastle United at
St James' Park in a 0–0 draw on the opening day of the
2011–12 Premier League season. On Saturday 20 August, he started at left-back and played the full 90 minutes in a 2–0 defeat at the hands of a
Liverpool side that picked up its first win over the Gunners away from home in 11 years. On 28 August, Sagna missed Arsenal's game against
Manchester United at
Old Trafford due to illness. Sagna sustained a leg break during a match against
North London rivals Tottenham Hotspur after a challenge by
Benoît Assou-Ekotto forced him to land awkwardly. On 29 January 2012, Sagna came off the bench against Aston Villa as an 89th-minute substitute to mark his comeback. On 26 February 2012, he started in the North London derby against Spurs, scoring a header from a
Mikel Arteta cross and inspiring Arsenal to come back from being 2–0 down to go on and win 5–2. He sustained another leg break of the same leg in the final home match of the season against
Norwich City, which ruled him out of
UEFA Euro 2012 in June 2012.
2012–13 season In October 2012, Sagna marked his return to the first team by starting in Arsenal's 1–0 victory over
Queens Park Rangers. On 3 November, he started and played the full 90 minutes at right-back against Manchester United at Old Trafford, a 2–1 league defeat. In his absence with a broken leg,
Carl Jenkinson started for Arsenal and earned rave reviews, but Sagna continued to be Arsenal's first-choice right back upon his return. On 9 February 2013, due to an injury to centre-back
Laurent Koscielny during warm-ups, Sagna was forced to fill in as a central defender against Sunderland. He helped a ten-man Arsenal win 1–0. On 28 April 2013, Sagna committed a mistimed tackle inside the penalty box on
Robin van Persie in a 1–1 home draw against Manchester United, conceding a penalty to bring the score level after a second-minute Arsenal goal from
Theo Walcott.
2013–14 season Sagna remained Arsenal's first choice right-back at the start of the season, fighting off competition from Carl Jenkinson. He scored his first goal of the season, his fifth in Arsenal colours, against
Stoke City on 22 September, heading in
Mesut Özil's free-kick, securing a 3–1 win for the Gunners. On 17 May, Sagna started in the
2014 FA Cup Final as Arsenal beat
Hull City 3–2 at
Wembley Stadium, his first trophy at the club. It was announced on 27 May that Sagna would not extend his contract with the Gunners, which was set to expire at the end of the season. Although Arsenal offered him a two-year extension, Sagna was believed to be "90 per cent certain" of leaving the Emirates, thus rejecting the contract extension. Additional sources understand that Manchester City and a number of top clubs in Europe had expressed an interest in signing him. Sagna said he did not sign a new deal with Arsenal because "the discussions did not go in the direction that he wanted".
Manchester City It was announced on 13 June 2014 that Sagna had agreed to a deal with Manchester City to join the reigning
Premier League champions after his contract with Arsenal was set to expire on 30 June. He was City's first signing of the summer and signed a three-year deal, taking the number 3 shirt. He left the club at the end of his contract in June 2017.
Benevento On 3 February 2018, Sagna signed with
Serie A side
Benevento Calcio for six months and a year in option. On 29 April, Sagna scored his sole goal for Benevento with 90th-minute header in their 3–3 draw to Udinese.
Montreal Impact On 8 August 2018, Sagna signed with
Montreal Impact in
Major League Soccer for the remainder of the 2018 season, with an option for 2019. Although the option was not taken up, Sagna subsequently signed a one-year contract to stay with the club for the 2019 season. ==International career==