Piper was educated at Rawlins Community College, and came through the youth ranks of hometown club Leicester City. After signing a professional contract in 2000, he made his first team debut in the League Cup on 9 October 2001, playing the whole of a 6–0 home defeat to Leeds United. After another appearance in a 4–1 league defeat to Liverpool, he was loaned to Mansfield Town, for whom he played 8 times. He impressed there, and scored his first senior goal against Swansea City. On his return in January 2002, Piper played 27 games as Leicester fought relegation from the Premier League. Although Leicester were ultimately relegated with a mere five league wins all season, Piper made his mark in the club's history by scoring the last ever competitive goal at Filbert Street against Tottenham Hotspur as Leicester won 2–1.
Sunderland signed Piper from Leicester in August 2002, for a fee of £3,500,000. Despite initially impressing, Piper's time at Sunderland was mostly an unhappy one, suffering a number of serious injuries, resulting in him having 10 operations in 3 years. It was later found that Piper had a rare and previously undiagnosed condition in his knee, meaning he missed most of the 2003-04 and 2004-05 seasons due to injury and rehabilitation.
Following Sunderland's promotion to the Premiership in the 2004-05, Piper was included in Sunderland's squad for the pre-season tour of USA and Canada, playing in two friendlies against American opposition. Although Piper was said to be fit, Sunderland manager Mick McCarthy was reluctant to rush Piper back into the first team, and made just one start against Cheltenham Town in the League Cup. This was to be Piper's final appearance for Sunderland, and his contract was terminated by mutual consent in January 2006 following an unsuccessful trial with Coventry City. He had made just 29 appearances, including 15 starts, in three and a half years at Sunderland.
In the summer of 2007, Piper participated in pre-season training at Mansfield Town, in an attempt to rebuild his fitness. However, he decided to retire before the start of the 2007-08 season. In March 2008, he started training with local side Anstey Nomads. He managed just one appearance before retiring from football completely
Piper is now in charge of the under 15s at Leicester.