Dolan, 23, moves to the Catalans in a free transfer after coming off contract and rejecting new terms tabled by Rovers.
Dolan has signed a three-year deal with Espanyol and told the club's website: "I'm excited. The club is amazing. (It's a) beautiful city. Me and my family are very excited for this new journey. It's an honour to play for Espanyol.
"La Liga is one of the best leagues in the world, so (it's an) exciting opportunity for me to come and showcase my talent.
"The main thing is for me to give 110%, every single game. I'm an exciting player. Skilful, direct, want to get fans off their seats."
Dolan said: "We can definitely keep pushing up the table higher, to be a solid La Liga team.
"Last season the team did very well but we aim to keep pushing higher and hopefully me joining the team, we can."