Signed after a successful trial, Olsson joined Rovers from Swedish side Högaborgs BK on transfer deadline day in January 2006.
A left-sided player, Olsson is equally comfortable at left-back or further forward down the flank. He prorgressed quickly from the Academy and Reserves to be a valuable member of the first team squad.
At international level, Martin has played through all youth levels and marked his senior debut for the Sweden squad with two goals as a second half substitute in a 4-2 win against Bosnia-Herzegovina in May 2010.
He also played in all three of Sweden's games in Euro 2012.
Signed a new five-year deal in June 2010 that sees him contracted to the Ewood Park club until the summer of 2015.