A hooker, Danny made his debut for the Newcastle Knights in 1997. Danny was a member of Newcastle’s 2001 premiership-winning team. Danny was appointed captain of the Newcastle Knights following the retirement of Andrew Johns in 2007. Danny played 221 games for Newcastle over 12 seasons (58 tries). In 2009, Danny joined the Leeds Rhinos. Danny was a member of Leeds 2010 and 2011 Challenge Cup final sides and Leeds 2011 premiership-winning side. Danny played 82 games for Leeds over 3 seasons (15 tries, 1 goal). In 2012, Danny returned to the Newcastle Knights. Danny captained Newcastle in 2012 after Kurt Gidley was ruled out for the season due to injury. Danny played another 37 games for Newcastle over 2 seasons (3 tries, 1 goal).
From 2001-2008, Danny played 5 matches for Country Origin (1 try). Danny captained Country in 2005 and 2007-08. In 2011 Danny captained the Exiles. Danny played 21 matches for New South Wales from 2002-08 (2 tries). Danny captained New South Wales from 2004 to 2008. Danny played 24 test matches for Australia from 2001-06 (2 tries). Danny captained Australia from 2004-05.
In 2014, Danny was appointed assistant coach of the Newcastle Knights. In 2015, Danny took over as head coach of the Newcastle Knights following the sacking of Rick Stone. Danny coached Newcastle for 6 games (2 wins). In 2016, Danny returned as an assistant for the Newcastle Knights. In 2018, Danny joined New South Wales as an assistant coach.
In 2020, Danny was appointed General Manager of the Newcastle Knights.
In 2004, Danny was awarded the Dally M Medal. In 2019, Danny was inducted into the NRL Hall of Fame. In 2023, Danny was inducted into the NSWRL Hall of Fame