On 8th January 2010, Norwich City signed USA Under-23 international Zak Whitbread from Millwall on an undisclosed fee. Zak is a left-sided centre-half who has missed the first half of the 2009/10 season after being sidelined this season by a hip injury.

Although born in the USA, Whitbread grew up primarily in the north of England in Merseyside although 5 years were spent in Singapore when his father Barry was the coach of the national team

He began his career with Liverpool, joining their centre of excellence at age eight. He worked his way through the academy before joining the reserves in 2003. His first match in the Liverpool jersey took place in 2003 in an exhibition match against Thailand during the club's Far East Tour. He came on to the pitch after the start of the second half. 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 Champions League qualification campaign. He made a total of six first team appearances for Liverpool

He joined Millwall on loan in the 2005/6 season before joingin them permanently in June 2006. He played 92 times in four years with Millwall, losing the League One play-off final to Scunthorpe in 2008/9.

He played for the United States under 20s team in the 2003 World Youth Championship. He started every match and scored his first goal for the U.S. to help the squad reach the Quarter Finals.

Paul Lambert said “Zak was somebody I always liked. I never thought I could get him, to be perfectly honest and then things transpired and I managed to try to sell the club to him.I think he'll be terrific here once he gets fully match fit and once he gets right involved, he will be a big player for us. We just need to get him up to speed and I hope it's not too long before he's right in the mix"

He made 4 appearances in 2009/10

After a slow start to the 201/11 season due to injury, impressive form for Norwich in the post-Christmas period saw him called up to the USA full squad for the first time. Unfortunately injury ruled him out of the games against Argentina and Paraguay in March 2011

Norwich won promotion to the Premiership, on 2nd May 2011 with a 1-0 win at Portsmouth with Whitbread playing a key role (23 appearances, 1 goal) for the Canaries. Whitbread finished the 2011/12 season with 21 appearances as Norwich finished 12th in the Premier League

On 17th May 2012, Whitbread was one of five players whom Norwich announced would leave the club on 1st June as their contracts would not be renewed. He joined Leicester on a two year contract in late July 2012

On 30th September 2013, Whitbread joined Derby on a three month emergency loan. He had made four appearances for the Foxes during 2013/14 to date. Although a calf injury kept him out of action for two months, Derby extended his loan at the beginning of January until the end of the 2013/14 season.

Whitbread was released by Leicester at the end of the 2013/14 season. He had played 21 games for Leicester. He signed a one year contract with Derby on 25th June 2014. He was released by Derby at the end of the following season.

In July 2015, he was reported to be training with Sheffield United. He nearly went to America in the summer of 2015 and was training with New England Revolution, but he'd just had a son and so thought it wasn't the right time to make the move.

On 16th October 2015, he signed a short term contract with Shrewsbury until January 2016. He then signed an extension until the end of the 2015/16 season.