In 2012, 19-year-old Solomona recruited out of Melbourne's youth system to play as a winger for the Melbourne Storm Under-20 team. He participated in just 13 games for the club during 2012 National Youth Competition season, and despite suffering from a fractured fibula in Round 13, he scored eight tries from those 13 games.
Solomona promoted to the Melbourne Storm's senior squad around a year later. In January 2014, soon after his contract with Melbourne Storm came to an end, he signed to London Broncos. But after the club's relegation, he was forced to move to the Castleford Tigers towards the end of the season.
In 2016, at the age of 23, Solomona broke the record by scoring 37 tries in a single Super League season in a match between Castleford and Catalans. He went on to finish the season with a spectacular performance of 42 attempts, of which two were in the Challenge Cup competition.
Danny made his international debut as a rugby player on October 8, 2016, for Samoa in their match against Fiji.
Solomona took a controversial step on 13 December 2016, when it was announced that he would be exiting from the rugby league, where he was playing for Castleford Tigers, to join rugby union and play for Sale Sharks in the Aviva Premiership.
This was despite the fact that his contract with Castleford Tigers still had two years left in it. Many took this to be a greedy move, citing that while his salary with Castleford Tigers was £50K per year, Sale Sharks were willing to pay him around £250K per annum. The case finally ended in June 2017 with Castleford and Sale reaching £200,000 settlement over the player.
On 29 March 2017, Denny was subsequently called up to the senior England squad for their 2017 summer tour to Argentina. He still maintains his involvement with Sale Sharks.
In November 2016, Denny announced an engagement to his girlfriend, the British model and former Ex On The Beach star Jess Impiazzi. The duo is having an on-and-off affair for over two years. They are yet to get married.