Prychynenko joined the first team on 26 February 2011 being named as a substitute against Aberdeen and on one further occasion. Due to injury he failed to make his debut that season despite that his under 19 form earned him a new three-year contract extending his stay until 2014. In November 2011 he joined Raith Rovers on loan until January 2012 to gain first team experience. On return from Raith, Denis made his first team début for Hearts as a late substitute in a Scottish Premier League match; a 3–0 win over Aberdeen. He was an unused substitute as Hearts won the 2012 Scottish Cup Final.