Zaretska stunned the crowd at the Crystal Hall as she completed an impressive 8-1 victory against the same opponent who had beaten her earlier in the tournament.
"I'm very proud to win the gold medal," said the 19-year-old, according to the official Baku 2015 website.
"I cried not just during the national anthem but during the final too. As I got more and more points I knew in my heart that I had the victory."
The hosts currently lead the medals table with six golds, one silver and five bronze accolades.