After the relocation of the club to Milton Keynes, Dack chose to leave to join the academy of Charlton Athletic, where he spent three years before being released at the age of 14.
[8] He enjoyed a prolific pre-season in 2012 including a four-goal haul against Royal Engineers,[9] which attracted attention from Gillingham manager Martin Allen,[10] leading to his professional debut on 14 August 2012, in a 2–1 victory over Bristol City in the Football League Cup.
[12] He scored his first senior goal on 4 September 2012 in the Football League Trophy away to Crawley Town and signed a new three-year contract the following day.
[13] Dack received his first red card as a professional for violent conduct against Southend United on 18 September 2012, having come on as substitute, after first winning a penalty.
[20][21] In the January 2016 transfer window he was reportedly the subject of three bids, including one of £2 million, from Championship side Bristol City, but all three were rejected by the club.
Achieving promotion to the Championship in his first season with Blackburn, Dack finished as the club's top scorer, finding the back of the net on 18 occasions in 42 league appearances.
Despite the step up in level, Dack continued to display his talent, finishing as the club's top scorer for the second season in a row, with 18 goals in all competitions, 15 of which came in the Championship.
[33] Following the news, Dack made his official return for Blackburn days later on 26 December, coming on as a substitute for Lewis Holtby in the 62nd minute of the 1–1 draw with Sheffield Wednesday.
Dack helped turn the fortunes of his side around, being involved in the build-up of all three of the club's goals, whilst directly assisting Tyrhys Dolan's 59th-minute header.
[45] In an interview with LancsLive reporter Elliott Jackson, Blackburn's director of football Gregg Broughton stated that a combination of finances and inability to assure greater playing time resulted in the club's decision to let Dack depart.
[49] An attacking midfielder, Dack has described himself as adopting a "free role behind the two strikers in the final third to go and pick up the ball, get into good positions and create and score goals".
[51][52] Interviewed by Sky Sports in February 2016, Dack suggested that the model for his own style of play was former Chelsea and England international Frank Lampard.