“What can I say, Germany – we are world champions,” Charr roared after his unanimous decision victory in Oberhausen landed him the vacant WBA world title.
“I dedicate this title to Germany, the country which gave me a chance and built me up.
“This is my gift to you all.”
Charr is Germany's first world heavyweight champion since Max Schmeling reigned from 1930-1932.
On Saturday, Charr was the clear winner after bringing Ustinov to his knees in the eighth round and the judges scored the fight 114-111, 116-111 and 115-112 to the German.
Anthony Joshua is the reigning WBA 'Super' heavyweight champion and the victory over Ustinov could open the door for Charr to a bout with the British boxer.
The win for Beirut-born Charr, who arrived in Germany as a five-year-old, completes his remarkable comeback from two setbacks which would have ended the careers of a less-determined boxer.
In September 2015, he was left fighting for his life after being shot in the stomach following an altercation at a kebab restaurant in Essen.
Charr returned to the ring just seven months later, bearing the scars of the attack on his abdomen.
Then came another setback earlier this year when both hips had to be replaced.
“In the last two years, I have experienced everything that one possibly can,” said Charr.
“From being shot to having two new hips, but I gritted my teeth.
“The doctors told me, it is a medical miracle.”
Charr seemed to be in trouble in the first six rounds as the 2.02 metre-tall Ustinov, who had a 22.5 kilo weight advantage, dominated the fight.
However, as the Russian tired, Charr got stronger.
In the seventh round, Charr had the Russian on the ropes and although Ustinov withstood the blows, he was forced to his knees in the eighth.
A vicious left hook cut the Russian under his left eye, but with blood streaming down his face, Ustinov was saved by the bell.
Charr finished the stronger for a deserved win, the 31st of his career
Raised in Berlin and Essen, this was Charr's second shot at a world title.
His previous attempt ended in a fourth-round defeat when he was stopped by ex-WBC champion Vitali Klitschko in 2012.