It took Gorshkov more than 11 months to capture the image using hidden cameras in Russia's Far East, the only place on Earth where Amur, or Siberian, tigers are found.
He was rewarded with the prestigious prize on Tuesday, according to a press release from the Natural History Museum, which runs the competition.
Sergey Gorshkov's picture of a rare tigress hugging a tree earned him the top award at the Wildlife Photographer of the Year 2020.
Sergey Gorshkov/Wildlife Photographer of the Year
"It's a scene like no other. A unique glimpse of an intimate moment deep in a magical forest," said Roz Kidman Cox, chair of the judging panel.
"Shafts of low winter sun highlight the ancient fir tree and the coat of the huge tigress as she grips the trunk in obvious ecstasy and inhales the scent of tiger on resin, leaving her own mark as her message."
Amur tigers were hunted almost to extinction in the last century, said Tim Littlewood, jury member and the Natural History Museum's executive director of science, and are still threatened by poaching and logging.
"The remarkable sight of the tigress immersed in her natural environment offers us hope, as recent reports suggest numbers are growing from dedicated conservation efforts," said Littlewood.
Winners were announced at an online awards ceremony featuring Catherine, the Duchess of Cambridge, Tuesday, with Gorshkov claiming the top prize.
Liina Heikkinen was crowned the Young Wildlife Photographer of the Year 2020 for her picture of a fox.
Liina Heikkinen/Wildlife Photographer of the Year
Winners of other categories include Paul Hilton's picture of a young pig-tailed macaque, which scooped the Wildlife Photojournalist Story Award, and Frank Deschandol's remarkable photo of two wasps, which topped the Behavior: Invertebrate category.
Finnish photographer Liina Heikkinen was crowned the Young Wildlife Photographer of the Year 2020 for her image of a fox protecting the goose it caught from five siblings.
"A sense of furtive drama and frantic urgency enlivens this image, drawing us into the frame," said Shekar Dattatri, wildlife filmmaker and jury member.
"The sharp focus on the fox's face leads us straight to where the action is. A great natural history moment captured perfectly."
Winners were selected from a shortlist of 100 images and will be exhibited at the Natural History Museum in London before embarking on a UK and international tour.