The 29-year-old was one of six victims involved in a knife attack in a Milan supermarket which left one person dead.
Mari was with his wife and son when the incident happened.
The former Flamengo defender, on loan at Monza from Arsenal, has been ruled out of action for up to three months to make a full recovery.
A 47-year-old Italian man has been arrested by police as the culprit.
A statement from Serie A club Monza said: "Pablo Mari was discharged from the hospital this morning, returned home and now begins a period of absolute rest.
"AC Monza sincerely thanks Professor Osvaldo Chiara and all the professionals of the Trauma Center of the Niguarda Hospital in Milan.
"Pablo, we are waiting for you!"
Monza will face Bologna without Mari on Monday and coach Raffaele Palladino has reiterated that his side will be going all out for their Spanish defender.
"It's not that we didn't want to play. The first news shook the whole group, and it's normal that we were shocked," head coach Palladino said when asked about not postponing the game.
"Initially we thought about a postponement, but the team reacted well, especially when they learned that Pablo was out of danger.
"A bad week, but at the same time beautiful. Pablo Mari is a miracle worker. Our duty is to play and go on the pitch and give everything also for our team-mate. We have no regrets over not postponing."
Mari has made eight Serie A appearances this season, scoring one goal.