Cllr Neil Bannister, the authority’s chairman, Deputy Lieutenant Richard Everard and Cllr Bill Zilberts, Mayor of Lutterworth, attended the short town centre ceremony in Church Square.
They were joined by veterans, service organisation representatives and other guests before the flag was hoisted on the council’s Symington Building.
The event marks the build-up to Armed Forces Day on Saturday (June 25).
Cllr Bannister said: "We in the Harborough District are immensely proud of the servicemen and women who dedicate their lives to serve our country.
“I am especially privileged to play my part in this flag raising ceremony to highlight the tremendous work and sacrifices made by all our armed services."