Akpan made 63 appearances for the Royals, having joined from League Two side Crawley Town in January 2014.
The 23-year-old, who has won four international caps for Nigeria, has signed a two-year contract with Rovers.
Akpan started his career with Premier League Everton and also had a two-month loan spell with Hull City prior to joining Crawley in 2011.
Find all the latest football transfers on our dedicated page.
Blackburn Rovers have signed midfielder Hope Akpan from Championship rivals Reading on a free transfer.