Miller was chosen 81st overall and has a chance to start at guard this season for the Bills. The 6-foot-2, 312-pound from Louisville started 47 of 48 games with the Cardinals.
Williams was chosen 155th overall out of Florida State. The 6-foot-1, 225-pound running back finished his college career ninth in Seminoles history with 22 rushing touchdowns. He ran for 1,419 yards on 241 carries at Florida State.
After the signings of tight end Nick O'Leary and wide receiver Dezmin Lewis Tuesday, four of Buffalo's six draft picks have signed with the team.