Published : 17 Aug 2016, 07:22 PM
Oumiha, greeted upon his entrance by loud boos from fans who continued to wave Brazilian flags and crank up the volume throughout the bout, took the silver.
Cuban top seed and 2012 bantamweight bronze medallist Lazaro Alvarez, beaten by the Brazilian in the semi-finals, and Mongolia's Otgondalai Dorjnyambuu won bronze.
With chants of 'Brazil, Brazil' echoing around the arena, the 27-year-old claimed the first two rounds on all three judges' scorecards.
The man in the red corner even turned crowd-pleaser in the second -- dropping his guard and showboating, with the odd feint thrown in -- before Oumiha came back stronger in the third.
"This is the most incredible moment," he told reporters. "I am Olympic champion, my life has changed forever.
"I had a very difficult childhood, I had a very complicated start in boxing with no support at all ... and today I'm an Olympic champion.
"I knew I had to come after him, because he is so good on the counter-attack and there was no way I wouldn't be punched," he said of his tactics. "So, the goal was to receive one punch, and then land three or four on him."
Conceicao raised his fist to acknowledge the crowd's support long before the referee formally lifted it to declare him the winner.
As he stood on the podium with the gold around his neck, after embracing his family, the crowd stood and sang the national anthem.
"It was magnificent," Oumiha, whose medal was France's first in boxing since 2008, said of the atmosphere. "I was expecting it, we talked about it with the coach, but what an experience.
"We showed each other mutual respect and it was a good fight. It takes two to make a good fight," he added "I tried to give it my best shot but at the end of the day he was the better boxer.
"He had his whole country behind him, it would have been the same for me in France."