Chairman Dexter McNamara signed the bill Friday morning at the tribal government building in Harbor Springs. The marriage ceremony is to follow.
At least two other U.S. Indian tribes recognize gay marriage.
Michigan voters approved a ban on bay marriage in 2004, although federally recognized American Indian tribes are self-governing and not bound by state law. A spokesman for Attorney General Bill Schuette (SHOO-tee) says Michigan would not recognize the validity of same-sex marriages conducted by tribes.