Yashaswini shot 236.7 in the eight-woman final to take the top spot, finishing a whopping 1.9 points ahead of second placed Kostevych.
Kostevych claimed silver with a score of 234.8 while Serbia's Jasmina Milavonovic bagged the bronze with 215.7.
Yashaswini came into the finals after the topping the qualifiers on a canter with a score of 582. She started with 10.1, 10.5 and 10.1 and was third after the first five-shot series of stage one. She then shot a 10.6 which helped her get to number two and then reached the top with a 10.1. She finished at the top after the stage with a final shot of 10.0
She started the elimination with a 10.4 and a 10.0. This was followed by a 9.0 but that could shake her off the top spot. She followed that up with a 10.4. A 9.1 then briefly pushed her to second but then she shot a tremendous 10.8 to get back to the top. She dominated the eliminators after that and thus sealed gold.
She thus joins the list of shooters who have won quotas for India ahead of Tokyo 2020 which includes Anjum Moudgil, Apurvi Chandela, Saurabh Chaudhary, Abhishek Verma, Divyansh Singh Panwar, Rahi Sarnobat, Manu Bhaker, and Sanjeev Rajput.
This is India's third gold in Rio after Abhishek Verma and Elavenil Valarivan topped the men's 10m Air Pistol and women's 10m Air Rifle events respectively. With one more silver and a bronze, India are currently top of the medals tally in Rio de Janeiro with three more finals to go.
( With inputs from IANS )