Miller missed last week's victory against California with a sprained left knee ligament but participated in practice this week.
Kenny Guiton started at quarterback for the second straight game and wasted no time making an impact Saturday, throwing for a school-record six touchdown passes during the first half.
Although Miller could have played Saturday if needed, the star quarterback and Buckeyes coach Urban Meyer made a joint decision to rest the junior one more week, a source close to Miller told ESPN.
Miller, a Heisman Trophy hopeful, suffered the injury two weeks ago against San Diego State.
The fourth-ranked Buckeyes (3-0) play their Big Ten opener next week at home against No. 24 Wisconsin.
Guiton, who earned Big Ten Offensive Player of the Week honors last week against Cal, on Saturday surpassed the record held by John Borton (1952) and Bobby Hoying twice (1994 and 1995). Guiton was 24-34 for 215 yards and an interception as the Buckeyes took a 55-0 halftime lead.
Quarterback Cardale Jones started the second half for Ohio State against FAMU.
"It really doesn't matter to me who is in," Buckeyes receiver Devin Smith said earlier this week. "They're both winners."
ESPN.com's Austin Ward contributed to this report.