Alister MacPhee and his dog were going for a Wednesday evening dip at Bloomfield boat ramp, north of Cairns, when the reptile erupted from the shallows, latched onto his leg and knocked him over.
The 37-year-old broke free from the crocodile's clutches, but it quickly snapped into his dog and dragged it underwater.
Mr MacPhee suffered wounds to his lower leg and was airlifted to Cairns Hospital, where he's refused to speak about the incident.
Parks and Wildlife Rangers found the same crocodile about 200m from where the attack happened and shot it dead on Thursday night.
"This crocodile has built an association between food and humans and that's an unacceptable risk to the community and therefore we had to act," incident controller Michael Joyce said on Friday.
"A majority of our wildlife officers are trained to shoot crocodiles from a moving vessel.
"Shooting a crocodile is a one-shot process, it is a very challenging job to do and one they train a lot to do and they are very skilled at doing that.
"Imagine from a moving vessel - from one or 200m away - shooting a 50-cent piece. That's basically what they have to do."
Rangers later found the dog's remains inside the reptile's stomach.
The Bloomfield River is a well-known crocodile habitat, Mr Joyce said, so the incident should be a warning to people to be cautious.
"Swimming in croc country is a choice," he added.
"I suggest to people if they want to protect themselves and their families and their pets, is make good choices."
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