Richard Shucksmith came top in the animal behaviour category for the image in the British Wildlife Photography Awards 2014.
The marine ecologist and professional photographer took the photograph in June last year after watching a family of otters swimming off the Shetland Isles.
The 41-year-old at first thought the otter had caught a large fish, until the animal swam closer to the shore.
He said: "I had been out all morning and was walking back towards the car when I saw this puffin disappear out into the water. I saw one of the otters also go under and 20 seconds later came up with something in its mouth.
"At first I thought it was a big fish. I started taking pictures and followed it towards the shore. Then suddenly I saw that it was a puffin. I was completely taken back.
"I've seen otters catch birds before, but I think it's very rare for them to catch a puffin.
"It's probably a unique image. I don't believe there's a record until now of an otter eating a puffin."
Mr Shucksmith, who lives near Lerwick, on the Shetland Isles, won the overall category in the British Wildlife Photography Awards in 2011 for a picture of a jellyfish.
The awards celebrate both the work of amateur and professional photographers and the beauty and diversity of British wildlife.
Winning images were chosen from thousands of entries in sixteen separate categories.
This year the overall winning picture was The Tourist by Lee Acaster, his image of a greylag goose in London.