Paul Thirlwell came through the ranks at Sunderland and made his debut in 1999 when the club won promotion to the Premiership. He spent time on loan at Swindon the following season but also made 8 appearances for Sunderland in the Premiership. During his time at Sunderland, Thirlwel won a cap for the England Under-21 team in 2000. He stayed at Sunderland for another 4 seasons and despite making over 30 appearances in the 2003/2004 season, he was released after 7 years with the club. He was quickly snapped up by Sheffield United where he made 28 appearances before signing for Derby at the start of the 2005/2006 season.