Signed in August 2009 to provide an immediate presence in the centre of the Tottenham defence, where injuries had hit just before the 2009-2010 season started, but also as a long term successor for Ledley King.

Developed through the Clairefontaine centre of excellence in France and was originally at Metz, where he became a French Under-21 international in the six years he was there, but after making 88 first team appearances for the Ligue 1 side over three seasons, he joined Newcastle in July 2008 after a one week trial, impressing in a friendly at Doncaster Rovers.  His introduction into the side saw him paired with Fabricio Collicini in the middle of defence, although sometimes, he was played at left back.

The much sought 23 year old, was being touted as a transfer target for a number of Premier League club's following Newcastle United's relegation to the Championship.  However, Spurs won the race to snap him up and his performances in the struggling Geordie side had been one of the bright points of a poor season.  His pace and strength in the air and in the tackle make him a solid central defender, but he also has an ability to bring the ball out of defence to link with the attack.  Also, his tackling has drawn attention from referees, as he was sent off twice in his season at St. James Park, but made 34 appearances for the Magpies.

But it was Spurs who moved for the strong central defender and paid £8 million for his services and got a quick repayment on their investment.  Starting on the opening day of the season in a home game against Liverpool, his towering header wad the second in a 2-1 victory.  It was odd, as Sebastien had only scored one previous goal, while at Metz, in a 1-2 defeat at home to Strasbourg on 18th May 2007. 

Bassong made an immediate impact with a goal in his first game at home to Liverpool and played 28 times as Spurs qualified for the Champions League in fourth place, but in 2010-11, he found himself behind the experienced signing William Gallas and by the end of that campaign was frustrated enough to talk about leaving to play football regularly.  A week into the 2012-13 season, Spurs sold Bassong to Norwich City for an undisclosed sum with the player linking up with former Newcastle United manager and former Spurs player Chris Hughton on a three year deal.

Changed his international allegiance after joining Newcastle United to play for Cameroon, where his parents were born.