Phillips succeeds Jim Christian, who left after two years to coach Boston College. Christian was 49-22 at Ohio.
Phillips was 134-84 in seven seasons at North Dakota State. He now joins a school that went 25-12 this season and made it to the CollegeInsider.com Tournament quarterfinals.
''I simply cannot wait to start working with our players and helping them reach their potential,'' he said in a statement. ''I want our fans and my players to know that I will pour maximum energy and enthusiasm into Bobcat basketball.''
Phillips was an assistant at North Dakota State for three seasons before becoming head coach. Before that, Phillips was the director of basketball operations for three years at Wisconsin under Bo Ryan.
Phillips played at Wisconsin-Platteville under Ryan and in 1995 captained the Pioneers' undefeated national championship team.
• Christian leaves Ohio for Boston College