Voters who return their ballots without a signature must remedy the situation by 7 p.m. on Nov. 3 in order to have their vote counted.
Republicans are arguing to protect laws that restrict individuals from mailing ballots on the behalf of others and out-of-precinct voting.
The 18-day registration deadline extension is expected to result in an additional 65,000 Arizonans registered to vote in time for the upcoming election.
The decision was met with opposition by Gov. Doug Ducey, the Republican National Committee, the National Republican Senatorial Committee.
Just over 3,000 early ballots returned during the 2016 general election were rejected for not having a signature.
County officials authorized an emergency voting site for the tribe, but the recorder’s office says they have no plans to open a new polling place.
Elections officials say lawmakers like Rep. Shawnna Bolick have spread information about mail-in voting that is, "inaccurate and often misleading."