At a ceremony in Standoff, south of Calgary, Chief Charles Weasel Head placed an eagle feather headdress on Harper, whose face was painted with yellow and red stripes, the Calgary Herald reported. The prime minister was given the tribal name Chief Speaker.
The tribe made a significant break with tradition in the ceremony. Normally a male warrior escorts the inductee onto the ceremonial buffalo rug, but Monday's event saw Master Cpl. Melissa Whitegrass of the Canadian Armed Forces escort Harper.
Whitegrass fought in Afghanistan. Her spine was broken by a roadside bomb in May 2010, the report said.
Harper became the second sitting prime minister to receive the honor, after John Diefenbaker in the late 1950s.
Chief Weasel Head said he extended the honor to Harper for making a 2008 parliamentary formal apology to Indians for government abuses in the old residential school system that separated families and denigrated Indian heritage.
"I am deeply grateful for the honor you have bestowed upon me today," Harper said. "It is a bond of friendship which will inspire me in my service to you and all Canadians."