While in Singapore, Whitbread attended St Stephen's School and then United World College of South East Asia.

[4][5] Whitbread made his first team debut in the 2004–05 season, and played a number of games alongside Sami Hyypiä in Liverpool's 2005–06 UEFA Champions League qualification campaign.

After signing for Millwall permanently on a three-year contract in June 2006,[6] he featured frequently in the team's first eleven, starting 18 games for his new club in the 2006–07 season, before injuring himself in September 2006.

[7] Over the course of the 2008–09 season, Whitbread made 44 appearances, including the League One play-off final at Wembley Stadium, which Millwall lost 3–2 to Scunthorpe United.

He made his first start of the season in a 1–0 victory over league leaders Queens Park Rangers, helping Norwich to a first clean sheet in 10 games.

Whitbread started in the Canaries' first game back in the Premier League, partnering Ritchie De Laet in a 1–1 draw at Wigan Athletic.

He returned for the League Cup match against MK Dons, and started against Chelsea, but was withdrawn after 30 minutes with a suspected hamstring injury.

In the next fixture against Newcastle United, Whitbread was given a start in a 4–2 win for Norwich, playing well apart from giving the ball away for Demba Ba's second goal.

Whitbread scored his first goal for Leicester City, from a Martyn Waghorn corner, during a 4–1 win against local rivals Derby County on December 1, 2012.

Initially signing a short-term contract running until January 2016,[15] he made his Shrewsbury debut in an unfamiliar midfield role, coming on as a substitute in a 2−1 away defeat at Scunthorpe United.

On March 16, 2011, Whitbread was called into the United States senior team's camp for its friendlies against Argentina and Paraguay, but was unable to feature due to sustaining an injury while on club duty.