Despite competition from other Super League and Australian clubs, Vagana signed for the Bradford Bulls in 2001. He became one part of the Bradford Bulls' Awesome Foursome, a phrase coined by the media, alongside Stuart Fielden, Brian McDermott and Paul Anderson. Vagana played for the Bradford Bulls at prop forward in their 2001 Super League Grand Final victory against the Wigan Warriors. As Super League VI champions, the Bradford Bulls played against 2001 NRL Premiers, the Newcastle Knights in the 2002 World Club Challenge. Vagana played as a prop forward in Bradford's victory. He also played for Bradford at prop forward in their 2002 Super League Grand Final loss against St. Helens. Vagana played for the Bradford Bulls at prop forward in their 2003 Super League Grand Final victory against the Wigan Warriors. Having won Super League VIII, Bradford played against 2003 NRL Premiers, the Penrith Panthers in the 2004 World Club Challenge. Vagana played from the interchange bench in the Bradford Bulls' 22–4 victory. He also played for Bradford at prop forward in their 2004 Super League Grand Final loss against the Leeds Rhinos. Vagana played for the Bradford Bulls from the interchange bench in their 2005 Super League Grand Final victory against the Leeds Rhinos. As Super League champions Bradford faced National Rugby League premiers Wests Tigers in the 2006 World Club Challenge. Vagana played from the interchange bench in the Bradford Bulls' 30–10 victory. A destructive tackler and strong runner with the ability to off load the ball, Vagana rarely missed a game for the Bradford Bulls and became one of the most popular players at the club. He also wrote a weekly column for several Bradford newspapers and the Bradford Bulls' website. In 2006 Vagana was awarded the Bradford Bulls' Clubman of the Year Award. He signed a one-year extension on 18 August 2006 to keep him at the Bradford Bulls for the 2007 season. After a long absence he was called up by New Zealand for their game against Great Britain in 2006 but did not play in the match. In June 2007 Vagana signed another one-year contract with Bradford, signalling his intent to play out the 2008 season. Vagana was sent off for the first time in his Bulls career against Wakefield Trinity Wildcats on 5 August 2007. In August 2007 he was named in Bradford's team of the Century. In 2008 whilst playing for Bradford against Wigan Vagana broke his arm attempting to tackle Stuart Fielden. Vagana retired at the end of the 2008 season after 8 years with the Bradford Bulls. In 2009 and 2010 he coached the East Coast Bays Barracudas alongside Willie Swann.