Lucca, a 12-year-old German Shepherd, suffered injuries including the loss of a leg during a search for improvised explosive devices (IEDs) in 2012.
She received the medal at a ceremony at Wellington Barracks in central London.
The Dickin medal, founded in 1943, is awarded by the People's Dispensary for Sick Animals (PDSA) charity.
Lucca was trained by US Marine Corps as a search dog to sniff out munitions and explosives, and according to the Marines, protected the lives of thousands of allied troops.
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She instantly lost her front left leg and suffered severe burns to her chest.
Her previous handler Corporal Juan Rodriguez recalled the moment she was injured: "The explosion was huge and I immediately feared the worst for Lucca.
"I stayed with her constantly throughout her operation and her recovery. She had saved my life on so many occasions - I had to make sure that I was there for her when she needed me," Rodriguez was quoted as saying by the BBC.
She lives in California with her handler, Gunnery Sergeant Chris Willingham, but has been flown to London for the medal ceremony.