The 26-year-old’s current contract at Plymouth expires at the end of this month and he will sign terms at Rochdale on July 1.
“I’m really pleased to be here and I cannot wait to get started,” Alessandra told Rochdale’s official website.
“I have been a big admirer of the manager Keith Hill for a while.
“Keith was the manager of the youth team at Rochdale when I was playing for Oldham Athletic’s youth side and you have to admire what he did with them and what he has gone on to achieve.
“He’s done great things at the club over the years and I’m excited about working under him.”
Alessandra, born in Heywood, spent four years at first club Oldham before moving on to Morecambe in June 2011.
He joined Plymouth two years later and made a total of 102 appearances for the south-coast club, scoring 25 goals.
Alessandra added: “Keith contacted me and I was very pleased not only to be playing for him, but to move up a division and to come back home.”