The Ghanaian striker suffered a stroke back in 2015 which left him debilitated just two years after retiring from playing.
According to a number of reports in Ghana, he passed away in London on Thursday morning.
Agent Saif Rubie tweeted: "Just heard the news that one of my first clients ever Junior Agogo has passed away. Still can't believe it. One of my proudest moments in football is seeing him smash the AFCON in Ghana."
Agogo began his youth career at Hillsborough in 1995, moving up to the senior squad in 1997. He made two first-team appearances for the Owls.
Overall, in his professional career, he played for fifteen different clubs over the next fifteen years and had particularly successful spells at Bristol Rovers and Nottingham Forest - and also spent a brief spell north of the border at Hibernian.
He spent time in the US at Chicago Fire, Colorado Rapids and San Jose Earthquakes.