Alice Nkom has spent a decade defending people accused of practising homosexuality.
Homosexual acts are illegal in Cameroon and carry a five-year prison term.
Ms Nkom described the award, which she received from the German branch of Amnesty International in Berlin on Tuesday, as a “prize of hope”.
“Being gay in Cameroon is like being in hell,” she told the BBC‘s Newsday programme.
“Permanent jail, permanent harassment, permanent violence and discrimination. From your family to the workplace to everywhere.”
The 69-year-old lawyer became the first black woman to be called to the bar in Cameroon in 1969.
She vowed to continue her work despite being sent death threats and warnings from government officials that she could face imprisonment.
The campaign for gay rights in Africa has been hit in recent weeks by a new law in Uganda which allows life imprisonment for acts of “aggravated homosexuality” and also criminalises the “promotion of homosexuality”.
Africa remains the continent with the toughest anti-gay laws, with homosexual acts punishable by death in Mauritania and South Sudan and parts of Nigeria and Somalia.