Appearing in black spider-themed swimwear, Romashina and Kolesnichenko finished top of the pile in the women’s duet after their free routine, ending with a total of 195.9079 points.
That put the duo comfortably ahead of China’s Huang Xuechen and Sun Wenyan in second, with Ukrainian pair Marta Fiedina and Anastasiya Savchuk taking home the bronze medal.
For Romashina, 31, the title is her sixth at the Olympic Games – adding to her double gold at both the Rio and London Games and single title in Beijing – putting her out on her own as the most successful Olympian her sport has ever seen.
The Muscovite also has a remarkable 21 world championship titles to her name.
The gold for Kolesnichenko, 27, was her second at the Olympics after she won the team title in Rio.