He became a national Football League referee in 1994, having previously served five years on their assistant referees' list. He was later granted FIFA status in 1999 allowing him to officiate international fixtures.[2]
In 2002, Riley refereed the English FA CupFinal between Arsenal and Chelsea, which he later stated was "the highlight of my career".[3]
Riley took charge of the 2004 Football League Cup Final, between Bolton and Middlesbrough, in a game that saw all three goals scored within the first 25 minutes. He awarded a penalty to Middlesbrough after seven minutes and cautioned five players during the course of the game. Riley failed to spot penalty taker, Zenden, kicking the ball twice.
Riley also headed England's refereeing team alongside assistants Philip Sharp and Glenn Turner at the UEFAEuro 2004 finals.[4]
Riley refereed the controversial 2004 match between Manchester United and Arsenal, also known as the Battle of the Buffet, with the result ending Arsenal's record-breaking 49 match unbeaten run.[5]