Following in the footsteps of fellow midfielder Alan Judge, Rovers have brought back another exciting Academy graduate, who has gone on to forge a promising career away from Ewood Park.
The 23-year-old - who played under Rovers boss Bowyer at youth level - joins for an undisclosed fee and has penned a three-year deal, which runs until the summer of 2016.
"Alex is someone I know well from back in the youth and Reserve team days here," said the Rovers manager.
"He's another player who I feel didn't fulfill his potential here. He went away to Crystal Palace and played towards the back end of the season and just missed out on the Play-off Final.
"He was hungry to come back here and make his mark, which he was unable to do the first time round. That hunger and desire is what we need."
Marrow began his professional career at Rovers, joining the Academy as an 18-year-old in 2008, before quickly making the step up to the Reserves.
After a loan spell with Oldham Athletic during the 2009-10 season, the midfielder moved to Crystal Palace on a three-month loan in August 2010 and impressed enough in his 18 appearances to earn a permanent deal in January 2011.
Marrow spent the first half of last season on loan at Fleetwood Town, before returning to Selhurst Park and playing a part in Palace's successful push for promotion.