Robert Thornton was in Norwich's Under 16 squad in 1999/2000 and made 1 appearance for the Under 19s in their 1-0 victory over QPR on 22nd January 2000. The Cambridge United website revealed in late April 2000 that Robert, who hails from Gorleston, had been offered and accepted a youth team contract at the Abbey Stadium.

He was released by the U's in the summer of 2002. Returning to Norfolk, he has signed for Great Yarmouth Town.

In the summer of 2008, Rob signed for Norwich United having "returned to the area" according to the Pink Un of 9th August 2008. He quickly moved on to join Wroxham