Sherwin joined Canterbury as a five-eighth with pinpoint goal kicking. He was a regular member for the under 19's squad and played in the Preliminary Final against the
Penrith Panthers which they lost. In 1998, Sherwin was playing on the wing for the reserve side. He broke the club's record for most points scored in a reserve team for a season with 170 points. He played in the eventual premiership victory over Parramatta. In 1999, he started playing half-back for the reserve side. Due to the injury of
Ricky Stuart, Sherwin got his first opportunity in first grade football. In 2000, Sherwin became a regular member of the Canterbury-Bankstown squad, playing at five-eighth. In 2001, Brent continued his success in the top grade, mainly playing off the bench. Due to injury, Sherwin was unable to play in the Semi Final against
St. George Illawarra. In 2002, he had a great season as he became the regular half back for the Canterbury Side, and got his first taste of representative football, As he was selected to play for City Origin. In 2003, he was again a regular member of the team. He played in the Preliminary Final, But lost against eventual runners-up the
Sydney Roosters. Sherwin played halfback for Canterbury in their
2004 NRL grand final victory over cross-city rivals, the
Sydney Roosters. In 2005, Sherwin's season was cut short due to a season-ending injury. In 2006, he came back with great form and played in the Preliminary Final which they lost to eventual premiers the
Brisbane Broncos. In 2007, Sherwin started the season in the lower grades, but early in the season returned to top grade and played for the remainder of the season. He played in the elimination final against arch-rivals the
Parramatta Eels, but Canterbury went down 25-6 ending their season, which would also turn out to be his last game playing for the club. == Castleford Tigers (2007–2010)==