Dangerfield graduated from the AIS-AFL Academy and toured South Africa in early 2007. In October 2007, he won the 100m and 400m titles at the Victorian Secondary Schools Athletics. Whilst at school he was also a school captain at Oberon High School.
Dangerfield's selection caused immediate controversy as he spent his first AFL year studying in his home state, Victoria, and could not train with the club consistently, while other possible selections such as Brad Ebert began their AFL careers in the senior side. During 2008 he played for the Geelong Falcons in the TAC Cup while studying and training with Adelaide when possible. Despite his disadvantages, he played two games for the Crows late in the 2008 season and showed promising signs.
In 2009 he changed his guernsey number from 19 (retired in order to assist the launch of the club's "19th Man" campaign) to the number belonging to former Adelaide captain Mark Ricciuto, 32. In that year he became a regular in the Crows' side, with his style of play likened by fans and commentators to Ricciuto. He received an AFL Rising Star nomination in round 3 for his performance against Fremantle at Subiaco Oval. In total Dangerfield played 21 games in 2009 and averaged 13 disposals and a goal per game. He continued to develop his game in 2010, playing 19 matches and kicking 26 goals.
Dangerfield was given more responsibility in the midfield in 2011, which he relished, playing every game and averaging 17 disposals. He also won the Grand Final day sprint in 2011, which he would reprise in both 2012 and 2013. In 2012 Dangerfield emerged as a star of the competition, playing in the midfield full-time and racking up 600 disposals for the regular season, ranked tenth in the AFL. He was selected in the All-Australian team for the first time and finished seventh in the Brownlow Medal. During the season he re-signed with the club for three years, to a very positive reaction from Crows supporters.
Dangerfield had another outstanding season in 2013, being selected again in the All-Australian team and finishing top five in the Brownlow Medal. Called upon at times to play as a forward due to injuries, he kicked a career-best 31 goals, second in the club's goalkicking, and ranked highly in several statistics despite being tagged heavily. In 2014, he was named action co-captain alongside Rory Sloane due to regular captain Nathan van Berlo's absence through injury. He defied injuries and taggers to again play a key role for Adelaide, leading the club in disposals and ranking first in the AFL for contested possessions, while finishing fifth in the Brownlow Medal. His season included a 41-possession game against reigning premiers Hawthorn, a record for an AFL match at the Adelaide Oval.