The Spartans (19-5, 8-3 Big Ten) are a game behind conference-leading and third-ranked Ohio State, setting up a big game Saturday on the road against the Buckeyes.
The last-place Nittany Lions (10-15, 2-10) have lost five straight and eight of nine.
Michigan State's Adreian Payne matched a career high with 12 points and freshman Branden Dawson also had 12, scoring in double figures for the fifth straight game.
Tim Frazier scored 19 on 6-of-18 shooting for the Nittany Lions.
Penn State posed a brief threat by pulling within five points midway through the second half, but Green made a layup on the next possession.
Frazier later made a jumper to make it 55-49, but the Nittany Lions couldn't stop Green from making a three-point play on the next trip down the court with 7:03 left in the game.
The Spartans closed the game with a 22-8 run, restoring the rout and improving to 15-0 at home this season.
Penn State, which has lost all seven of its road conference games, got off to an awful start and finished poorly.
The Nittany Lions missed their first eight shots and needed nearly 8 minutes to score, but didn't trail by too much because the Spartans also started 0-for-8 before beginning to make shots to build a 9-0 lead.
Michigan State led 33-19 at halftime despite making just 27 percent of its shots and turning the ball over 10 times because Penn State shot 21 percent and had nine turnovers.
The Spartans were effective early in the second half on offense but later let the Nittany Lions score 10 straight points.
Green played a big role in dashing Penn State's hopes with shots, assists, rebounds and defense.
Michigan State's Keith Appling had 10 points and seven assists.