"I'm very pleased to be here," the new midfielder told the club's official web site. "After a long summer finally we are ready to go.
"I'd made up my mind to leave Italy, obviously it wasn't that simple, but Blackburn made an important offer and I'm happy to be here.
The Australian-born midfielder started his footballing career in his home country, but then moved to Italy to continue his football education.
Previously with Torino, Grella decided it was time for new challenges.
"I'd spent ten years in Italy and I learnt a lot there," added the 28-year-old. "I'm happy that I started my career in that country, but it was just getting a little bit stale there. Italy is still an important country to play in but the English Premier League had something special that I wanted to be involved in.
"There's a certain enthusiasm about all the stadiums of England, the way that the people enjoy their football. I think the clubs have invested a lot of money in bringing in the top players and they have improved the football as a consequence.
"It is an enthusiastic league to watch, the opportunity was there and I thought it would be good to measure myself against such a good league."