The victors will square off in the November general election.
Glenn Millsaps of Collidge and Kevin Taylor of Maricopa are competing for the Democratic slot while Independent Ty Morgan of Florence is running unopposed.
The four Republican candidates for sheriff are Derek Arnson, current Sheriff Paul Babeu, Jack McClaren, all of San Tan Valley, and Tom Bearup of Queen Creek.
The candidate from each party who receives the highest number of votes will advance to the November 6 General Election.
Pinal County voters also will narrow their options for the Board of Supervisors, the body of elected officials that sets tax rates and oversees the county's budget.
The growing county is required by state law to add two new seats to the currently three-person board, and this race is a crowded one with 24 candidates, 17 of them Republican, vying for five seats.